College soccer has fielded an NCAA championship for 50 years now, and several of those have been held in Big XII country. While it's not as big a sport here in the States as it is elsewhere in the world, it's still likely the fourth or fifth sport on the American sports landscape, battling with hockey and NASCAR for the spots behind football, basketball, and baseball. Youth soccer has been turning out stellar (by American standards) athletes for over a generation. It's the premier fall sport for many schools at which football is absent. And yet two of the most major conferences in the country have yet to embrace it by formally fielding teams in men's soccer. No schools in the Big XII field men's soccer teams at all, while two SEC teams--South Carolina and Kentucky--field teams which compete in Conference USA. While I draw the soccer comparison, however, I will note that lacrosse holds one advantage to advancement in these conferences that soccer does not--it doesn't take place during football season.
We know one of the big obstacles to the expansion of lacrosse is Title IX. In the case of most schools, to add men's lacrosse, they'd also have to pick up an additional women's sport, likely women's lacrosse to remain compliant. This would be a significant burden on most programs, as these would be additional expenses that likely wouldn't make revenue. Interestingly enough, if anyone could afford it, it would be the SEC and, to a lesser extent, the Big XII. But those spoils, of course, will go as much as possible back to football, the undisputed champion in the regions of the country represented by both of these conferences.