Certainly sufficiently so that USAF and USN are now collaborating on a common (or at least mostly common) 6th gen fighter to replace both Super Hornet and Raptor.
Excuse me? The lesson learnt is that the common airframe concept was a disaster (nothing learnt from the F-111 then) and that for the next generation they should develop common modules, such as engine, sensors etc, which can be incorporated into task specific airframes (just as the F-14 was designed around modules intended for the F-111, reinventing the wheel again).
In fact, the total opposite of that which you claim.....
Where Commonality Can Work in a Sixth-Gen Fighter