There are still plenty of difficult to kill monsters in the game. Especially if you don't insist on having the best setup and proper numbers. Is there an NM that requires a whole alliance to kill? Not really, but was that really what made things difficult?
Certainly even though Aby NM's aren't as likely to wipe the party, I find I'm definitely thinking more through the fight than I would in a Kirin zerg. Paying attention to proc messages. Watching for magic and physical resistance on the NM's. Stunning certain TP moves and -gas. THe system is far more fun than the old zerg or gtfo strategies of old.