Doors open? You bet. Seats out? That one takes a 2-star's approval for each flight (as per AR 95-1...although we can debate specifics and exceptions). Long story short, seats out is a huge safety hazard, especially in a crash sequence.

Well, that's the short version. There are risk mitigation measures (restraints), but I can kind of see the Army's reluctance to allow seats-out on a regular basis.