Including one because of history, money, or any other reason to the detriment of any of the several better teams that would be left out (including the best team from that conference) is silly.
You can disagree with the suggestion, but to suggest that this approach would be "silly" is itself somewhat silly given that all 4 major professional sports leagues more or less follow this approach, especially in football and baseball. There have been numerous times where a shitty division winner in the NFL or MLB has made the playoffs over much better teams that didn't win their division, and even in the NBA and NHL if one conference is significantly better than the other deserving teams will similarly get left out.
I think some are also downplaying the boost a larger playoff would have to engagement (and, thus, money): since more games would have playoff implications, more games would "matter" down the stretch (the Pac-12 championship, for example, would have taken on much greater importance). So you can disagree with the Power-5 auto-bid suggestion but it's not like there are not legitimate reasons to go that route.
(FWIW, I also don't think the 8-team format with P5 conference winners and 3 at-large teams (or even 2 at-large teams and the best non-P5 team) creates a "good chance" that significantly better teams would get excluded. If you just look at the final rankings from this year, if we had the 8 team format it would be Clemson, Oklahoma, UGA, Ohio St., USC, Alabama, and then one or both of Wiscy and Auburn depending on whether you think UCF should also get an auto-bid. I don't see any team outside of that group that could make a claim as the best team in the country. And yes, in this scenario USC gets a minor "advantage" for playing in a conference that was bad this year but again that's no difference than an NFL team getting an "advantage" because they play in a bad division.)
