Short term thinking, and probably how Iger and Co think. Those malls may be a dime a dozen, however this particular mall sits on the only piece of land that would allow contiguous development between the properties Disney currently owns. It allows Disney to build hotels along the stretch between DL & DCA and the third park(or Iger's version of ESPN Zone or Disney Quest) and control the guest experience between. It's only a 10 minute walk between properties, if Disney can route guests through more Disney owned property that's a big deal aesthetically and financially.
Disney bought 75 acres of land back in 1998 for over $100 million and has been content to use it as a parking lot, $80 million is a rounding error in terms of what Disney spends, they're currently sitting on $12 billion in cash(at current inflation that diminishes in purchasing power by over $700 million annually).
I'm not convinced they do know what they want. I'm fairly certain DisneylandForward is just a ploy to get Anaheim to change zoning and allow them to build the Eastern Gateway, "Look we're gonna develop these parking lots and that means we need a replacement."