There'll always be debate about who gets left out no matter how many teams, but if they go to 16 then come on, anyone that gets left out wasn't going to win it all. I think 16 seems just right in my book, but even eight would be a huge improvement.
As a Gators fan, the playoff size debate always makes me think of 2006. Leading up to the end of the season, Florida had one loss to Auburn and Florida's AD(or maybe president? I don't remember for sure) was leading the way for a group of schools to propose a playoff instead of just the top two in the BCS rankings.
It ended up pretty much of a toss up between Florida and Michigan to play undefeated Ohio State, but Florida got in and of course stomped the Buckeyes... I thought it was a perfect example of why a playoff was needed, the clear best team almost got left out and many thought they should've been left out until they proved it on the field. I thought the Gators would use it to show how badly the BCS system almost screwed up. Instead, Florida went "Oh hey we won, nevermind, we're cool with the way things are!"
Always makes me wonder, though, if things would look different now had the defending champion gone through in leading the way saying we need to change how we get that champion instead of scrapping it all.