Realizing that I could go back and edit tags was handy. Quite a few times I post without 'em and go back in later after I've noticed what others are using.
Yeah, I could go back and edit, I guess. But there still is no list of available tags, or appropriate ones, or whatever. I'm sure if I was committed to the platform fully, I would instinctively remember whether it is #SillySeason or #sillyseason, or I might actually remember the BETTER version of that tag that KB came up with... but I will never find that post again, just to discover the tag he used, so I can edit my post with an appropriate tag... that has some unknown value or reason for existing...
Which is why I often use the most simple, straightforward, topic appropriate tag. Community tags on the other hand, I'll get a bit more creative if the first two tag slots are already well filled. If not, then I'll tag it with once again, a simple, straightforward, topic appropriate tag.