I'll tell you why winning the conference in football, basketball, and baseball in the same year is more important than winning a national championship in any of the 3.
Somebody wins a natty in each sport every single year. That means there's been like 400 national champions of football/bball/baseball, etc.
You know how many times a school has won all 3 in the conference in the same year? It just happened for the 3rd time ever. EVER. EVAR.