I kept hearing that the driver behind the Maryland to B1G was money. Evidently, the school's finances were / are under some pressure.
Not sure if Maryland had any particular issues with ACC, but the college president was sold on the Big Ten sending an extra $10 million / year (or so) their way, due to BTN revenue,
more lucrative bowl deals, better TV contracts, etc.
It is about money. For Maryland, I think the ACC put itself too much in front of UMD's ability to generate income off football and basketball that pushed it into the B1G. Its ACC football future was to half-filled stadiums and body-baggers, losing autonomy while also losing direct access to the best games by way of preferential treatment. The basketball forcast saw a lot more NIT and CBI's than NCAA tournaments.
The B1G isn't going to fill the void of the Virginia rivalry, or Duke basketball, but the B1G won't stand in the way of UMD's profitability. The B1G understands (and is betting on) their potential in that respect.
If Florida State, or any other ACC member, said to the conference, "we want to go fb independent, but we'll play 5 games with you in fb on rotation to help our scheduling, and of course we'll still grace you with all our other sports in the ACC"; wonder how that request would go down?
When you treat an outsider or partial newcomer better than your own, that's not good.
To some extent, I think Texas and Oklahoma are on this path. We just don't know yet what they've tossed around when they were talking to conferences. I'm quite certain they'd bring the Cotton Bowl with them, special tie-in and all.