I don't think you understand what's coming. Think a chintzy Wilponized version of Wrigleyville in Chicago or Yawkey Way in Boston, with plans for another two sports arenas in the immediate area.
http://ny.curbed.com/tags/willets-point
I agree with your implication. I think it's crazy to waste money on this development there, but Wilpon is doing it on the public dime, so for him it makes sense.
Most likely if they ever spend real money on payroll again, it'll be when the project happens so there'll be more fans to spend at the "baseball neighborhood".