Maybe I'm crazy, but I don't think this is particularly difficult to understand:
1)
UConn fans prefer the B1G to joining the ACC. The ACC, looking to augment its football and basketball, raided the Big East for Syracuse, Pitt, and Louisville in the past few years. These moves destroyed the Big East as we know it. Furthermore, twice, UConn was targeted for expansion, however, BC threw up its roadblock, claiming a desire to "be New England's team" and prevent UConn from joining. Argue that BC does not have the power to do this if you like, but do not be surprised when we do not believe you. Member schools of a conference will not fight against the wishes of another if there is a viable alternative to pick. Sadly for UConn, Pitt and Louisville (with Clemson and FSU in tow) were satisfactory alternatives, and the member schools did not have to go against BC's wishes. Notice how rare news of a rejection hits the news wires. Query why UConn fans can readily link multiple sources with quotes as to why they were not invited. Usually, you hear news of the inner workings of a conference when an addition is imminent, not when a school was rejected. There is sufficient evidence to infer a hostility in the ACC to UConn, not from all members probably, but enough smoke exists here that you are blind to pretend there is no fire. Seeing the general hostility towards UConn, it should not surprise you that we prefer to join a different league given the choice.
2) Specifically for the ACC visitors, we DO NOT DEFEND THE ADDITION OF RUTGERS TO THE B1G. We objectively understand it. The B1G's expansion criteria is objective. They look for large, land-grant universities with AAU status, and those who can augment the value of the B1G Network. AAU membership is not the overriding factor, but it counts for a lot. First, they added Nebraska, a legacy football program with a national brand. Nebraska's name adds value to every game they play, making the addition valuable to the B1G network. While no longer in the AAU, they were members, a "like" university whose monetary value outweighed those factors. Maryland and Rutgers have between them
5.277 million cable television households. While athletically average to subpar, the financial value they add is clear. Charge $5 a month for each cable subscriber in those states (assuming you can), and annually, those schools pull in $316.6 million.
We think the B1G probably made a mistake with the Rutgers addition, but we know why they did it.