Seems like the stadium doesn't directly increase revenue (at least not much) but has a huge indirect effect. Goodison, as it exists and undeveloped, has a huge capital risk for the owner, as it may present immediate needs which require capital beyond what the balance sheet can offer. This may create (or cooperate with) a fiscally conservative position that prevents investment in players that can help now. An undeveloped Goodison also prevents further gate revenue, and certainly hinders some element of commercial expansion (although maybe we all agree that the commercial failings have been so widespread that nearly any sincere effort might provide a better return).
With a redeveloped Goodison or new Walton Hall Park Park, the capital needs can be clearly projected and the risk is low--already modeled in the debt service and revenue increases, and so the club could embark on direct investment in the squad without fear of large, unexpected capital outlays.
Maybe I'm simply (and unintentionally) regurgitating what's been written here or elsewhere before, but it seems that while a new stadium would not necessarily increase revenue (at least not significantly), the current situation keeps revenue under lock. Thoughts on this?