Yeah, pika is more of an ID system vs. prefixed-api-key which seems to be more oriented around just API keys, which makes sense. However, advantages of timestamps in IDs are that you can create unique IDs based on the current timestamp; bits which, in other ID systems, are usually just random - which feels like a waste imo. Also, knowing when a resource was created when debugging is very helpful.
Of course if you don't like the id's that MongoDB generates by default you can always the supply your own. The only constraint on the _id field is that it be unique as we automatically apply a unique index. Effectively if you have a unique key for your data you should use _id for it as it saves you an index. (We always index _id).
I don't agree. Your examples (UUID1, UUID4) are much longer strings and contain no useful information. UUID1 contains the device's MAC ID, UUID4 is just random bits.. vs a functional ID system like pika or Snowflakes which make use of those random bits by embedding a timestamp - something which might actually come in useful for some.
