If the top 100 would get votes like the top 20 now, that would probably be not so good, as further down witnesses (including myself) have no backup server yet (that would double the costs). But there could be a better way than now, here is the current reward distribution:
Definitely looks like there could be a better way. Intuitively you would think that best would be a curve that sloped gradually from left to right. Or at least had much less of a drop off after the first 20. But, as you say, there's not much appetite to change it.