I'm not in favor of a desperation grab, but the Big 12 rightly should be at least looking at options for expansion. There is no guarantee the conference will get as lucrative a deal relative to other conferences when it comes time to renew.
I have absolutely no idea whether or not this is true, but I feel like Big 12 was one of the more recent conferences to renegotiate its TV deal, which may be a reason it's done so well revenue wise.