Here's my concern: a 32 team playoff means 30 playoff games. Currently there are 40 bowls. While more bowls could definitely be created, it seems almost certain that some existing bowls would be turned into playoff bowls - leaving more teams out. Thereby increasing revenue, exposure, and practice time for the haves and leaving more have nots on the outside looking in. As a practical matter, the "haves" would get the nod. not too mention travel issues if they were neutral site games anyway (getting a basketball team across the country on short notice is one thing, an entire football team and semis full of equipment is another).
If the first round were a home-hosted game, it would make that less of a problem, make travel 50% easier (and there would have be to considerations in seeding also), and guarantee a revenue stream (50% ticket allotments, opening up after ~3 days of sale or something). While it would hinder the feel of the first round, we'd be left with a 16 team neutral playoff that would only really require 8 additional games (since we already have a 4 team playoff). That's seems more doable.
Best part - more US vs. THEM matchups. The P5 couldn't just contract bowls with other P5 to avoid losses.