I don't think fiddling with the % is going to have any meaningful impact on things. In fact, if people think rewards bring such value, I'm actually wondering why nobody proposes a bigger reward pool.
Okay. So, what solution do you have in mind?
This is already possible, so either it won't work, or people don't find content here valuable.
If people aren't willing to tip but eager to vote & inflate, we must ponder over this problem.