The issue is that history is a big deal for college bowl games to the point where the dividing factor between divisions is literally bowl games being in the title of FBS versus FCS. half the fun of college football comes from traditions and bowl games are traditions. It's not that the removal of the San Diego Credit Union bowl is bad, it's the 800 million they made from tickets, hotels, and restaraunts over the last 20 years they made. We're already hitting points where 5-7 teams make bowls, and we'd run out of "good" bowls to fill an 8 team playoff. Instead of two games, we'd have all 6 BCS bowls (first round plus semis) and each conference would lose having the ability to have two teams in BCS tier bowls.
FCS playoffs also start the same week fBs teams are required to have a bye for army navy, so there would have to Be major rule changes and the removal of conference champ games to make it work which although is feasible, I feel would be worse overall