Hmm. Interestingly, this is already how fleetwide skills work, except not being based on the number of crew but generally on the total deployment points - but then those are strongly correlated. E.G. The "Crew Training" skill increases max CR more when you have fewer total DP.
So, yeah, I wonder. This would be very much in line with that, and if the effect of this reverse veterancy of crew was to act as a multiplier for CR effects, and just changed based on how much crew you had. It'd also preempt the question of "why do marines have it and crew doesn't", since the answer would be "look, they have something else!".
The aspect of counteracting the difficulty curve a bit is really nice, though. And, again, it's in line with other mechanics boosting the smaller-fleet playstyle.
The only thing is that this would incentivize ships with lower crew requirements, i.e. high tech ships. If it wasn't for that... but, wait - it doesn't actually have to be based on crew numbers. It could be based on deployment points, too; the idea of being able to hand-pick great crew for X combat capability worth of ships makes roughly the same amount of sense.
Yeah, I think I like this a lot, especially coupled with intrinsic_parity's suggestion as to the effect. Going to have a look to see how straightforward it is to give it a shot.