I had considered downvoting your prior node, though I chose not to. Let me explain a few of the reasons I though to downvote your node.
You don't offer any support for your position.
From the context of the discussion it's clear that you feel that your proposal would solve the problem of thank you nodes (that I assume you feel are of value) being devalued by the comunity. However I think that does not enforces a value but rather a lack of value on such nodes. Worse still it can be seen as an acknoledgement by the author that nodes marked as such are not of value on their own.
Your solution is likely to cause more problems than it solves.
From time to time trolls wander in to PM, some times they gain a few levels before unleashing their vitriol on their fellow monks. Before long those levels are retracted as they lose experiance points. If trolls could simply mark their posts as "Omit from Voting" and feel free to flame, and then downvote those that respond (and get the exp from that voteing) there would be little reason to refrain from doing so. Voteing is supposed to be a comunity feed back on a node and a limited form of control on behavior. If you remove the risk of penalty you remove the pressure from the comunity to behave properly.