Expanding the autobids makes more regular season games matter. Not less.
I apologize if I am making the wrong assumption, but you are proposing an 8 team playoff with the winner of each of the Power 5 conferences receiving an automatic bid along with 3 "At Large" bids. The problem with giving the winner of the conference championship an automatic bid is what happens if a team that would never have had a chance to make the playoffs before the CCG wins that game. I would define a team that doesn't deserve to go to the Playoffs, even an 8 Team Playoff, as one with at least 4 losses. Personally, I feel that in most situations a 3 loss team wouldn't deserve to belong in an 8 Team Playoff (An example of one that would deserve to be in an 8 Team Playoff is this season's Southern Cal). Below are some examples from this season and a few from the past few seasons that had teams in a CCG, but had they won would have had no business belonging in an 8 Team Playoff
ACC
2009 GTech vs Clemson - Clemson was 8-4
2012 FSU vs GTech - GTech was 6-6
Big Ten
2016 Wisconsin vs Penn St - If Wisconsin won, then I don't believe they deserved to be in The Top 4 this season because they lost to both OSU and Michigan. Their best wins would have been Penn ST and against an LSU team that was not the same team after Miles was fired (LSU was a completely different team on offense). I think there is a strong case to not include them in an 8 Team Playoff as well.
2012 Nebraska vs Wisconsin- Wisconsin was 7-5 that season, need I say more.
Pac 12
2015 Stanford vs USC - USC was 8-4
2011 Oregon vs UCLA - UCLA was 6-6
SEC didn't have any recent teams with at least 4 losses, the most comparable would have been 2010 when Auburn played USC who entered the game 9-3.
Other than 2014 and 2010 there has been at least 1 CCG with a team that had they won would have had no business making the Playoffs. Granted there were no upsets in the games listed above, but imagine if a 6-6 UCLA won the Pac 12 in 2011 or a 6-6 GTech won in 2012. One might counter with that is what the 3 open slots are for, but the problem with this logic is that one of those slots would be taken by the team that lost the CCG, thus taking away a slot from a more deserving team than a 6-6 conference championship. Another argument is that it hasn't happened yet, the 6-6 teams have lost. I would counter by saying this is football, and anything can happen in a game, aka injury to starting QB, weather (Remember the rain this season when NCSU beat ND. Sorry, but that wasn't a game based on skill, but luck in who could snap the ball and who could hold on to it).
My point is that for those proposing an 8 Team Playoff where each of the conference champions from the Power 5 receive an automatic bid, then it has the potential to open up a can of worms much worse than what the CFPC did this season by putting OSU in over Penn St.