I would venture that the Harrier wasn't a compromise at all. It was built from the wheels up to provide CAS (or BAI in cold war scenarios) operating from small strips and austere bases.
Some would venture that it was and remains one of the finest ML and LL CAS platforms the world has yet created.
Does this mean it has a low top speed...errr, yes...but that's not in the spec for a CAS platform. Ditto radar - although it would have been helpful. Could it carry PW3? Yes with massive limitations but when did a JTAC ever talk us onto 'One times reinforced bunker, in the open'?
That specialisation will, inevitably lead to it being less capable in other situations...but it is (just my opinion) fundementally incorrect to call it a compromise.