I know a bit about this question but I find that there are quite a lot of diverse opinions on the subject?
I know from a players perspective that more options is almost always good. But on the other hand if it has multi-player more means higher complexity (meta game) both for the developers as well as players.
On development complexity and time constraints always go hand in hand. Another would be resource and platform constraints. Possible economic ramifications of holding back for later is sometimes a reason as well.
So from people experience here aside from the above when should features be cut or be for later release?