The bowl system could have been improved with the "+1" format that was floated around for a while but never put in place. My biggest complaint with the playoff is that we still have the subjective committee / voting nonsense, and that it has completely devalued all bowl games outside of the playoffs. I want at least some teams to have an objective path to the postseason. I feel that should be the P5 conference champions, they should all get an automatic bid. That removes subjectivity from what is likely, but not guaranteed, to include at least a handful of the best teams in the country. My preference would then to expand to 8 teams with 3 at large bids to the 3 that win the subjective dog and pony show, with perhaps 1 spot reserved for the best G5 team, to ensure that any of the top teams that don't win their conference still have a way in.
The one problem I don't know how to solve is seeding. Given the huge scheduling discrepancies CFB can't seed based on win percentage, so the dog and pony show goes on. Ideally I'd like to see mandated scheduling rules for all teams (all play same # of conf games, P5 non-conf opponents, limits to FCS opponents, etc.) so there is more consistency and teams can be more accurately seeded, but we are a long way off from that and it still can't be perfect with 130 teams and so many conferences.
The knock on a big playoff field was always that it devalues the regular season, which is one of the things that historically makes CFB great. If you reward the top seeds with home games or byes in the playoffs, this protects the integrity of the regular season to an extent, but if we get about 12 teams I think the regular season will really start to suffer.