Should modern combat jets go back to dedicated designs?

with all these projects being continually delayed, expensive, complicated, and weight gain..

would it have been cheaper in the end to have stuck to dedicated designs?

for example: instead of JSF, a dedicated aircraft for V/STOL, and a dedicated aircraft for the Navy and Air Force? (Perhaps two instead of one design).

Instead of putting a bunch of skills into one airframe, separate them into either dedicated aircraft (i.e. Su-25 and MiG-29) or variants of a common design (AJ-37 and JA-37, Tornado IDS and ADV)