I agree
This is about the only area where OOTP falls behind Mogul. I would like to see an all around deeper financial simulation but a good first step would be to allow for stadium funding and building.
Just my personal opinion, but a lot of the things that have been added to OOTP in the last few versions have been to cater to the manager side of things.
I wish the focus for a few versions would shift back to the GM/owner side of things.
But I do realize that Markus has to create the game for a wide audience. How I play the game is just a small slice of the overall user base.
Not to get too far off point though, this is a very good idea and one that would add a lot to the game. But I don't see it making it in for OOTP 14. This would be a major feature to add (to be done correctly) and would probably have to wait until version 15