I take it you don't fly KLM often ? Aside from the check-in issues, nothing you mentioned is new or surprising to us frequent flyers on AF/KLM.

Well correction, it's surprising you liked the catering on KLM in Y, because very few of us based in Europe think it's any better than canteen quality. I skip the snack served before landing on AF/KLM in Y in general, they're all rubbish. As for not having a gate immediately upon arrival, that's not really specific to KLM, rather JFK doesn't have enough gates probably- there are a lot of late TATL flights thru midnight as JFK doesn't have a curfew.

There are a many carriers out of the NY area though; I think UA/LH have lots of correspondances to central and eastern Europe (LH has practically a monopoly) so that might work out better next time.