I think you're missing the point. The one thing the BE did that was brilliant was put its' conference tournament in The World's Most Famous Arena, smack dab in the middle of the greatest media market in the country.
Football has become the driving force in "college" (really semi-pro) athletics, but that doesn't negate the tremendous amount of money to be made in college basketball. Duke and UNC are already brand names up and down the East coast and nationally. As is Syracuse, which has an established and lucrative presence in NYC. Bring all of that cachet to Manhattan on an annual basis, and no other conference will be able to come close to the gobs of money and attention that the ACC will get. They'll OWN February and March. Period.
Where the BE was stupid from the word "go" was keeping operations in Providence, a backwater, second-tier city overshadowed by, well, everything around it. Greensboro is nice tradition, and I'm sure it's a quaint, bland, average second tier American city. So are Hartford, Pittsburgh, Buffalo, Indianapolis, Cleveland, etc. No one in their right mind looking to maximize media exposure, attendance, or dollars would pick Greensboro or Providence for their signature event.
By relocating the ACCT to the Garden, the ACC would effectively place their boot on the throats of the other conferences and be the basketball equivalent to the SEC football conference in terms of prestige, perception, revenue and all-out dominance.
All respect to Greensboro and the ACC tradition, but this ain't our fathers' ACC.