The only restrictions that make sense are time restrictions, and I don't think you can find a time-frame were every DCS fighter keep their Fox1 and the F-14 have to abandon its Phoenix.
Quick internet search :
AIM-54 : 1974
Super 530D : 1987
R-27R: ~1985
R-27ER : ~1990
AIM-7M : 1982
AIM-120 : 1991
There is no point to remove it other than "balance" or "fairness" that I find irrelevant to this sim.
Edit: Balance is already here, I would really like to see the turkey performances with 4 or 6 phoenixes, good luck turning or accelerating with that drag and load, not even talking about range limitations :D.