From the perspective of "a FL veteran" it's difficult to fully take a stance on the DRK/DRG/AST situation. I feel like the issue is coming from elsewhere to be honest, and I say that fully aknowledging that I sometimes still get killed by those premades.
The fact that FL draws in so many clueless people who are just here for their quick XP, the general western mentality about doing minimal (mental) effort is a bigger issue imo.
Try to follow a premade in your alliance if you spot one, and coordinate your efforts with mass killing on DRK pulls and see if you still find it that bad/unfun, and if it works do wonder why it's working (answer: because the people you're killing are just clueless).

An issue I would definitely agree with is the overabundance of CC and absence of CC resist: getting double polymorphed, triple pulled backwards, DNC charmed then MNK LB without the possibility to do anything about it, etc. Guard should never be able to be broken by anything, and it should prevent absurd one shot mechanics that take no skill to achieve (SAM). RPR and DNC forcing the DRK pulls to work everytime IS an issue unlike the pulls themselves. Guard should probably also be reworked to activate when pressed and not years later after all enemy damage has registered...

Regarding Battle High I really don't understand why people want that gone, for anyone who enjoys FL it's an additional reason to play, to get stronger and be able to do more for your team (or just for your own pride!). FL without BH would be so horribly flat...