FATEs are fun, and another thing which Heavensward completely killed are Levequests, which, while rather monotonous, at least offered some kind of questlike feel before they were bolted on as an afterthought forcing you to keep going back to Foundation. For people who like to play with a partner it doesn't feel very rewarding to level up in Heavensward after the first run-through of the main quest.
Ultimately any kind of grinding - POTD, FATEs, levelling roulette which keeps dumping you in Sastasha with half of your skills locked - leaves you unprepared for party play in some way. It's a separate issue entirely. People who prefer not to think about their role aren't going to start thinking just because you block FATE levelling.