My purely personal opinion: 50% per year is way too much, and there needs to be a sunset clause. It's very difficult to foresee how fast bandwidth will grow more than five years out and we also don't know what bandwidth is safe as a percentage of average domestic bandwidth or median domestic bandwidth or whatever.

I think you'll easily get a consensus based on actual, realised bandwidth data supplied by reliable sources combined with observation of the network to see if there is any evidence of either increased centralisation or of the limit hampering growth.