Like any good capitalist, they're looking for franchises where they can increase the value. NFL teams print their own money, while in the EPL you probably can only be a mid-lower table Premier League team (a la Crystal Palace) and hope to turn a profit - the big teams have to spend a shitload of money to keep up with the joneses and try to compete in the big international tournaments, while the relegated teams lose their big payout from being in the EPL. Us with a relatively new arena was a prime target for moneymaking, they probably bought us as much for - if not more for - the arena rights.