I like it. As mentioned above, it is easy for a bunch of Pats fans to scoff at inviting some 7th seed peasants into their playoff fun, but when you root for a team that has not been there in 12 seasons, the additional spots sounds attractive. Plus, I think you will get a scenario like the 2010 Packers every few years where injuries decimate the best team during a long stretch of the regular season, but they get healthy around playoff time and win the whole thing.
I don't think it really hurts week 17 that much, relative to what we have right now. It makes the 1 seed much more valuable than the 2 with the bye week and home field advantage if they ever meet, meaning very good teams will play hard to avoid the 2, just like they work hard to avoid the 3 or 4 now. Also, with the significant disparity between the 5 and the 7, I think the 3 becomes that much more valuable than the 4 seed, thus giving more incentive to play starters and top strategies in week 17, even if the division is sowed up early.
One thing I would like to see is the 5 seed getting home field over the 4 if they have a superior record, both overall and in conference.
In terms of a longer season, I would like to see 17 games, with an inter conference "rivalry" game every year (Raiders - 49ers, Jets - Giants, Cowboys - Texans) and the extra game played on a neutral site (like London, or LA) for each team, thus still leaving each team at 8 home and 8 road games. I think the NFL would love to have 6-8 LA games and 6-8 London games every year with the occasional Mexico City or San Antonio game thrown in.