Everything I've ever read about the guy as well as teen series of aircraft (F14, F15, F16 and F18) say he hated the F15 from the start.
The motto when the Eagle was being designed was "Not a pound for air to ground." This was consistent through the A model to the C model. But a funny thing happens when you design an aircraft with incredible performance; it can often succeed in secondary roles. This was true of the F-15, and it was also true of the F-14. This isn't something new, it harkens back to WW2 with the P-47.
Considering the success of the F-15 in all of it's models, I'd love to see what you consider is ruined about its design.
Also true of the Hawker Typhoon, built as a balls to the wall interceptor turned into a very very good light bomber.