Don't take it too seriously, it's just for fun. It really doesn't change the dynamics of a forum very much, and, regardless, if users really want it it should be implemented in order to retain them and prevent a forum from dying.
Often posts that were good in some way, whether simply amusing or informative, were thanked. Other times there were pointless thanks, thank parties, and no one really cared, so it didn't really matter much more than any other silly thread made in a place like Half Baked. Then there were thanks used simply because they agreed with a post, but this isn't much different than an upvote system like reddit, and without it people instead quote the post along with a short line to show their agreement/support, and don't add much to the discussion.
it seems that people would only be drawn to come back and post better, or at least in more of a way that is approved by the community.
I think this is an unrealistic expectation. The people that are that motivated by thanks aren't suddenly going to turn around and become quality posters in order to develop and vague unquantifiable sense of being valued by the community, which takes time.
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