I have, in the past, suggested that any conference that has not placed a team in the quarterfinals in the last five seasons, or the semifinals in the last ten seasons, should only be allowed one representative in the playoffs. That representative would, of course, be the conference champion. This additional requirement is just as clear and transparent as the existing criteria, but it would replace many teams that are not playoff caliber with other teams that are.
The Chicago Public League, to its credit, has already moved in that direction. There are some CPL conferences whose members are not eligible for the playoffs, and there are other CPL conferences that restrict the number of teams from their conference who will participate in the playoffs.
Under the proposal made in the first paragraph, Taft still would have participated in this year's playoff. That is because they play in the extraordinarily large 16-team "RED" conference the CPL created, and Phillips is also part of that conference. [Phillips won a state championship in 2017, and thereby has been a semifinalist in the last ten seasons.] However, Taft did not even play Phillips, nor Morgan Park (the conference champion). That type of artificial situation might need to be addressed at some point, but at this point in time I am merely offering a broad concept as a possible solution.
One doesn't see the NCAA offering multiple bids (to the year-end national basketball tournament) to the Ohio Valley Conference just because more than one team in the conference had a winning record. They don't because they exist and think in the real world where rational people understand there are qualitative differences between conferences. Yes, every team should have a chance to participate in the tournament/playoff, and they do (by winning the conference championship). But no, all conferences do not have to be treated the same when there is objective historical evidence demonstrating a qualitative difference.