I don't really care that much about ISU, KSU, KU, and Baylor (they have all said they will fight A&M's departure), but they do have a point. If the B12 dissolves they don't have the luxury of parachuting out and are totally screwed. You could argue who cares, but it will be pretty sad that post-B12 an entire swath of the country between the west coast and Mississippi will not be represented by a major conference. There are perennially mediocre programs in all the remaining conferences and as it sits now, the B12 is still stronger than the Big East, ACC and possibly Pac.
tl;dr blame Texas, the B12 leftovers have no choice.