I find ENY restrictions annoying, at best. That said, it has forced me to find other planes to fly that I've ended up enjoying- the LA5 being my latest toy that usually gets me through most ENY restrictions.
The rapid escalation of ENY values when you're trying to up is something I commented on here before. I find that EXTREMELY annoying, having to spend a few minutes finding a plane you can fly, being denied one, choosing another and being denied that one and on and on.
My suggestion, which few seemed to think was a good idea, was to have the current ENY restriction posted somewhere in the hangar so you'd know right off the bat where you stood as far as plane restrictions.
Either that, or have ENY useable planes listed in standard gray text and other planes that are ENY restricted in some other color. Save the red text for planes that aren't allowed due to fiter hangars being down or such.
I thought that might make choosing a plane a bit easier and quicker during ever changing plane restrictions.