As a creator in The Sandbox, it’s currently challenging to use spawn behaviors such as 
Replace Behaviour, 
Asset Spawner, or 
Drop to spawn different objects.
Current Workflow
Typically, we assign one preset per behavior per message, requiring a separate setup for each item or object. This becomes increasingly complex as more elements are added.
Dungeon Game: In a dungeon game, crates spawning random items based on messages would require individual instances for each item.
Skeleton with Random Loot: A single skeleton could drop various loot items if messages could spawn different objects.
Shop System: While rules handle the backend logic, setting up shop items could be much more efficient with a single spawner setup.
Different Enemy Waves: We could use one spawner to spawn all wave types by sending different messages.
City Builder: We could spawn various decorations (wooden, silver, golden doors) based on different selections, simplifying customization.
State Change: Possible for more complex state changes of entities, affecting behavior at different quest stages (start, middle, end).
Suggested Improvement
With a feature allowing different messages to trigger different items within a single instance and behavior, the setup would be far more streamlined.
I imagine the layout of the setup could look something like below or similar with the 
Animated Decoration.
If this request is met, it would improve our experience by optimizing the number of instances, expanding gameplay possibilities and creativity, and saving creators time on setup.