Reminding people about the ability to vote is not bad, because sometimes people forget about it. Besides it can work against you if your creation sucks in most people's opinions. So yes, it could backfire LOL.

The thing is that the above mentioned phrase "just rate, don't hate" is a good reminder to members to NOT flame someone's creation in the forum, but instead to post their opinion in the correct manner which is to vote. Otherwise threads can become derailed quickly by flame wars.

It's not illegal to say the above phrase. It is ONLY illegal if you attempt to filter out bad votes by telling people to only vote up.