I'm in the same boat as everyone who's already answered this question, and I so think such a move would largely regionalize the sport. Assuming that most folks feel the way that we do, it would mean that only the people who have a local-ish team to root for would still have interest.
The NFL is by far the most popular spectator sports league in North America, and I think part of that success is due to the fact that the whole country is involved. Only truly tiny population metro areas don't have a "local-ish" NFL team- the biggest is San Diego at #18, but they lost a team because of low local interest. The biggest metro that's never had an NFL team is San Antonio- which is #24 on the list.
Look at the SEC/B1G map- they'd be missing 9, 10, 13, 18, 19, and 20 before you get to #24, and that's if you make some stretches (i.e. saying that USC covers Charlotte, PSU covers Philadelphia, Maryland covers DC, Rutgers covers NYC, etc.)
Moreover, it's the distribution- you'd have 4 teams in Alabama and Mississippi, and only 1 each in the much bigger states nearby (Georgia and Florida), 3 teams in Indiana yet only one in Ohio, a team in SC yet none in the much bigger NC and Virginia, etc.