OK, in inverse order, Hockey East is the best collegiate hockey conference and UConn plays in it. B1G wants to be the best at everything, including hockey. Thus, UConn participation in Hockey East help greatly, especially if the Huskies are competing for a B1G slot with schools like Kansas, Oklahoma, etc.
As for the ACC, I have siad this elsewhere. Yes, UConn was overconfident about being the next one in. Yes, Jurich did a great job selling Louisville. Yes, Warde could have done more; but, at least he did not hurt UConn like prior AD's. But, in the end it did not matter.
When Maryland left, the ACC had 11 voting members and 3 pending/non-voting members in Syracuse, Pitt, and ND. To get into the ACC, UConn needed 2/3 majority of 7 'yes' votes. Of course, to save face, once 7 votes is secured, everyone is expected to vote 'yes' to save face. From the start, UConn had at least 4 solid 'no' votes - 1) BC, 2) Clemson, 3) FSU, and 4) Miami. In addition, there was a solid 'no' from pending member Syracuse and Pitt, who owed their P5 lives to Syracuse and BC, was told likely to follow along. Only 1 more school would have had to swing no, likely G Tech. UConn's vote was DOA before Maryland left and before anyone in Storrs could do squat. Louisville took advantage of that and won.