I just want to pop in and say I'd like to see this someday, but my motivation for it never was related to score-whoring.
I was thinking it would be a way to improve immersion - you've got this plane, you got it dinged up, so now you bring it back, land it carefully and make your way to a repair hangar and wait around while the guys work on it (with sound effects, external view enabled, might be cool to see a couple of figures in the hangar move around the plane and work on the affected areas). It has always struck me as less-gamey than landing, towering out and grabbing a fresh plane and rolling again in a few seconds, but people look at it different ways; what's gamey to some is not to others. I also understand how it might be used be score-potatos. Maybe a significant time penalty like 1 minute per item would discourage that. And if you land at a front line base, there's always the chance your hangar would be destroyed while you're in it. I think that would add some intensity, too.
EDIT: Was thinking, maybe the repairs could cost perks, and maybe the cost of the repairs could depend on the ENY value of the plane - e.g., P-40Bs cost nothing to repair, but LA-7s, N1Ks and Spit 16s would be more expensive. Then score potatos might consider using less-capable aircraft when running up a score - another way to give incentives for flying the less popular a/c.
That said, I'd rather see a P-39, the rest of the Japanese air force and updated cockpit art for the remaining planes first.