Sepulcher once talked about a similar voter incentivisation scheme in which those who voted received a small payout (25 grc or something). We've currently got a seriously poor voting participation rate; currently we're averaging about 50 mil out of 750 mil voting weight for recent foundation polls - very poor community voting participation :(
So you do have a good point, I think a manual reward system would be easier than hardcoding voting incentives within the client.
Yeah for me the voting itself is secondary, I just want to make sure people are engaged so they are less likely to drift off - voting reward is just a means to an end