I've said this in other places: never underestimate how much university presidents overestimate the value of BC (if that makes sense). They are transfixed by the Boston market (a place where many of them were educated at some point) and believe that BC brings *enough* traction in that market that they're thought of as a valuable piece. I don't think that anyone thinks of BC as a headliner or as a team that is ever going to be bigger than the Red Sox/Pats/Celtics/Bruins, but they are a solid "depth" school (excellent academics and location) that brings value to the league even when they're a bottom feeder (unlike, say, Iowa State or Washington State).
For the ACC (and I say this as someone that was convinced that UConn was going to go to the ACC instead of Louisville when Maryland defected), looking at it from the outside, I think it was MUCH more about FSU and other football schools pushing for more perceived football quality than anything about BC. BC might have had an objection to UConn, but honestly, I can't blame them from an unbiased perspective any more than Villanova keeping Temple out of the Big East for years, Florida not letting FSU into the SEC, or all of the Big Ten schools protecting their own markets. Having that conference advantage has shown to be more important to schools over and over and over again than creating a regional rival (especially in this era where TV markets and contracts are so important). The "it's better to create a regional rivalry" argument is always one that's advanced by the school that's left out and is then freely ignored by the school in the better position. I can understand the specific animosity toward BC from the people on this board, yet they're not really taking a different stance than Ohio State is with Cincinnati, Penn State is with Pitt, Florida is with FSU, etc.
Regardless, the ACC invite to Louisville seemed to be more about timing than anything. 1 year ago, Louisville likely would have never been considered, but I truly believe that the defection of Maryland was a complete shock to Jim Swofford (who despite what some people might say here, is VERY smart regarding overall college sports landscape) and that perceived football quality had to come as priority #1 in expansion (and it's not as if though Louisville has a shabby basketball program, either). That concern trumped everything else.