If you really want to be accurate the reason UConn is not in a major conference is due to fan support on TV, specifically for FB. Look at KU, they can still do quite well on TV when decent. They have a higher ceiling, and a higher floor than UConn.
I believe much of that is due to regionality of sports fans and UConn getting caught up in FCS level competition with all the crappy Northeast flagships that put no focus on FB.
So if you really get to the point it's the lack of UConn fans willing to tune in on TV. That has led to other schools like UCF, Cinci, Houston, etc getting opportunities where UConn did not.
If UConn could put up good TV ratings they would be in a major conference. It's that simple. So the people not showing up for games, not tuning in on TV, not donating $ to the AD , the lack of focus on FBS football in the Northeast for flagships, etc all combined.
But right now UConn really only has 1 outcome that is positive. The B12. A depleted ACC is really not a good option unless they only lose 2 teams. If they lose 6+ then UConn might be able to do something with BC Cuse, etc but options seem slim at that point.
IMO this is UConn's last chance to make a stable power conference. FOX and ESPN seem content with the B12 making it and the ACC seems to be getting ready to crumble. UConn needs to get in now before more valuable programs like Louisville, NCST, etc are available to the B12.
The worst outcome for UConn is UConn gets passed up once again, and the B12 adds some package of ACC teams. Those 3 conferences break away in all sports and do not include the Big East.