I can sympathise with people's hurt feelings but this IMO is the key point here:

Since the experiment started, I have seen a new sense of excitement with the platform from regular users that has not been there since I joined back in July. I have seen many users buying more STEEM, so that they can power up their accounts and gain additional influence.

I have experienced that myself! My vote actually means something now and I know for a fact I am not the only one because I have talked to others who feel the same way.

As you mentioned before I think it may be better to give whale accounts "investor" status with a higher level of interest and automatically cap them against voting above the equivalent of say 250MV and we combine that with a more linear reward curve.

It may even be feasible to get rid of interest on regular accounts completely and use that to fund the investor interest rate.