[mzr]

That was designed in the '60s by a prolific aircraft designer. It was quite a different time.

[hga]

But they continued that with e.g. the F-117 stealth fighter(-bomber), after Kelly Johnson was no longer running the show. The story of the prototype's development is stunning, see e.g. http://www.amazon.com/gp/product/0316743003/

As for the F-35, the TFX like requirements are its biggest problem (https://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvar... see also The Strategy of Technology if you want the whole picture).