I don't consider a 2 arena tier difference to be slight. However, you can still keep champions around if you wish, most of the power comes from putting equipment on them. For example, I dropped over 50k power just from removing equipment from 3 champions that I had no immediate use for except faction wars.
So no, people should not be ignoring these perfectly accurate player power posts. They shouldn't be throwing away champions they can use, but if they want to advance in the arena right now, then minimizing their player power is the quickest way to do so. You may or may not be able to find success in gold, depending on what your team looks like, but being able to farm silver medals in S4 is better than being stuck in bronze. You may not like it, but the efficiency of the strategy is not contingent on your approval.
As for Plariums promises, they rely on a couple of assumptions. One, that it will actually happen, which I'm not counting on considering their track record, and two, that it will actually fix anything, which... well, you get the point.