I remember being really into naval aviation when I was a kid, and I'd look at carrier air wings. There would be F-14s for air superiority, A-7s for light attack, A-6s for heavy attack, EA-6Bs for electronic warfare, KA-6Ds for tankers, S-3Bs for anti-submarine warfare, etc.
Now I look at a modern carrier air wing, and it's F/A-18E/Fs for air superiority, F/A-18E/Fs for light attack, F/A-18E/Fs for heavy attack, F/A-18E/Fs for anti-submarine, F/A-18E/Fs for tanking, and EA-18Gs for electronic warfare. Same for the Marine Corps and a bunch of foreign nations.
For that matter, the X-29 was itself a variant of the F-5, another lightweight, low-cost design that got a lot of mileage in different roles, including being the starting point for the F/A-18 design. Sometimes it pays to be cheap.
http://www.f-16.net/f-16_versions_article26.html
GD really wrung as much mileage out of the F-16 airframe as they possibly could, coming up with all sorts of weird proposed spinoffs from it. They bid on the fighter-bomber contract that was eventually won by the F-15E Strike Eagle, for instance, with a delta-winged F-16 they called the F-16XL (https://en.wikipedia.org/wiki/General_Dynamics_F-16XL), and they attempted to jam thrust-vectoring into the platform with the F-16 VISTA (https://en.wikipedia.org/wiki/General_Dynamics_F-16_VISTA).