when is a global unique id generator really necessary

we've been kicking around the idea of implementing a global unique ID generator for our distributed system. on one hand, it feels like a good way to avoid certain race conditions and simplify downstream processing that relies on unique identifiers. but on the other hand, it adds another moving part and potential point of failure. we're already using Snowflake-like IDs generated on each service, which works for most cases. so, when does the complexity of a dedicated global ID service actually pay off over local generation? curious to hear other folks' experiences and when you've found them essential