diff --git a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/SymbolVisitor.kt b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/SymbolVisitor.kt
index af74c80d9f6..f3cca65c927 100644
--- a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/SymbolVisitor.kt
+++ b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/SymbolVisitor.kt
@@ -38,6 +38,7 @@ import software.amazon.smithy.model.shapes.StringShape
 import software.amazon.smithy.model.shapes.StructureShape
 import software.amazon.smithy.model.shapes.TimestampShape
 import software.amazon.smithy.model.shapes.UnionShape
+import software.amazon.smithy.model.traits.ClientOptionalTrait
 import software.amazon.smithy.model.traits.DefaultTrait
 import software.amazon.smithy.model.traits.EnumTrait
 import software.amazon.smithy.model.traits.ErrorTrait
@@ -269,7 +270,9 @@ open class SymbolVisitor(
     override fun memberShape(shape: MemberShape): Symbol {
         val target = model.expectShape(shape.target)
         val defaultValue = shape.getMemberTrait(model, DefaultTrait::class.java).orNull()?.let { trait ->
-            if (target.isDocumentShape || target.isTimestampShape) {
+            if (shape.hasTrait<ClientOptionalTrait>()) {
+                Default.NoDefault
+            } else if (target.isDocumentShape || target.isTimestampShape) {
                 Default.NonZeroDefault(trait.toNode())
             } else {
                 when (val value = trait.toNode()) {
diff --git a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/JsonSerializerGenerator.kt b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/JsonSerializerGenerator.kt
index 981706b5665..609d32c3f80 100644
--- a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/JsonSerializerGenerator.kt
+++ b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/JsonSerializerGenerator.kt
@@ -178,7 +178,6 @@ class JsonSerializerGenerator(
         "JsonValueWriter" to RuntimeType.smithyJson(runtimeConfig).resolve("serialize::JsonValueWriter"),
         "ByteSlab" to RuntimeType.ByteSlab,
     )
-    private val serializerUtil = SerializerUtil(model)
 
     /**
      * Reusable structure serializer implementation that can be used to generate serializing code for
@@ -378,10 +377,8 @@ class JsonSerializerGenerator(
                 )
             }
 
-            with(serializerUtil) {
-                ignoreZeroValues(context.shape, context.valueExpression) {
-                    serializeMemberValue(context, targetShape)
-                }
+            rustBlock("") {
+                serializeMemberValue(context, targetShape)
             }
         }
     }
diff --git a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/QuerySerializerGenerator.kt b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/QuerySerializerGenerator.kt
index 23c8bbb4fb8..14c313f674f 100644
--- a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/QuerySerializerGenerator.kt
+++ b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/QuerySerializerGenerator.kt
@@ -96,7 +96,6 @@ abstract class QuerySerializerGenerator(private val codegenContext: CodegenConte
     private val serializerError = runtimeConfig.serializationError()
     private val smithyTypes = RuntimeType.smithyTypes(runtimeConfig)
     private val smithyQuery = RuntimeType.smithyQuery(runtimeConfig)
-    private val serdeUtil = SerializerUtil(model)
     private val protocolFunctions = ProtocolFunctions(codegenContext)
     private val codegenScope = arrayOf(
         "String" to RuntimeType.String,
@@ -208,10 +207,8 @@ abstract class QuerySerializerGenerator(private val codegenContext: CodegenConte
                 }
             }
         } else {
-            with(serdeUtil) {
-                ignoreZeroValues(context.shape, context.valueExpression) {
-                    serializeMemberValue(context, targetShape)
-                }
+            rustBlock("") {
+                serializeMemberValue(context, targetShape)
             }
         }
     }
diff --git a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/SerializerUtil.kt b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/SerializerUtil.kt
deleted file mode 100644
index 27293e43039..00000000000
--- a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/SerializerUtil.kt
+++ /dev/null
@@ -1,31 +0,0 @@
-/*
- * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package software.amazon.smithy.rust.codegen.core.smithy.protocols.serialize
-
-import software.amazon.smithy.model.Model
-import software.amazon.smithy.model.shapes.MemberShape
-import software.amazon.smithy.model.shapes.StructureShape
-import software.amazon.smithy.rust.codegen.core.rustlang.RustWriter
-import software.amazon.smithy.rust.codegen.core.rustlang.Writable
-import software.amazon.smithy.rust.codegen.core.rustlang.rustBlock
-
-class SerializerUtil(private val model: Model) {
-    fun RustWriter.ignoreZeroValues(shape: MemberShape, value: ValueExpression, inner: Writable) {
-        // Required shapes should always be serialized
-        // See https://github.com/smithy-lang/smithy-rs/issues/230 and https://github.com/aws/aws-sdk-go-v2/pull/1129
-        if (
-            shape.isRequired ||
-            // Zero values are always serialized in lists and collections, this only applies to structures
-            model.expectShape(shape.container) !is StructureShape
-        ) {
-            rustBlock("") {
-                inner(this)
-            }
-        } else {
-            this.ifNotDefault(model.expectShape(shape.target), value) { inner(this) }
-        }
-    }
-}
diff --git a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/XmlBindingTraitSerializerGenerator.kt b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/XmlBindingTraitSerializerGenerator.kt
index fc4f0198387..68e31a533a8 100644
--- a/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/XmlBindingTraitSerializerGenerator.kt
+++ b/codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/serialize/XmlBindingTraitSerializerGenerator.kt
@@ -73,7 +73,6 @@ class XmlBindingTraitSerializerGenerator(
 
     private val xmlIndex = XmlNameIndex.of(model)
     private val rootNamespace = codegenContext.serviceShape.getTrait<XmlNamespaceTrait>()
-    private val util = SerializerUtil(model)
 
     sealed class Ctx {
         abstract val input: String
@@ -517,15 +516,8 @@ class XmlBindingTraitSerializerGenerator(
                 inner(Ctx.updateInput(ctx, tmp))
             }
         } else {
-            with(util) {
-                val valueExpression = if (ctx.input.startsWith("&")) {
-                    ValueExpression.Reference(ctx.input)
-                } else {
-                    ValueExpression.Value(ctx.input)
-                }
-                ignoreZeroValues(member, valueExpression) {
-                    inner(ctx)
-                }
+            rustBlock("") {
+                inner(ctx)
             }
         }
     }
diff --git a/rust-runtime/aws-smithy-types/src/blob.rs b/rust-runtime/aws-smithy-types/src/blob.rs
index ab7ae30d3c5..1087b6d930c 100644
--- a/rust-runtime/aws-smithy-types/src/blob.rs
+++ b/rust-runtime/aws-smithy-types/src/blob.rs
@@ -31,6 +31,14 @@ impl AsRef<[u8]> for Blob {
     }
 }
 
+impl Default for Blob {
+    fn default() -> Self {
+        Blob {
+            inner: Vec::new()
+        }
+    }
+}
+
 #[cfg(all(aws_sdk_unstable, feature = "serde-serialize"))]
 mod serde_serialize {
     use super::*;