Was gonna wait till 7.1 to see what fresh hell pvp has in store but given that this thread is still going I'll throw my opinion in the ring.
I appreciate that the Op is addressing the different types of pvp in regards to their grievance as most who post forget or dismiss them.
1.) SHB FL was the best iteration of pvp large-scale for role based method
A.) the classes were better balanced with about an even amount of aoe & single target abilities as well as their own selectable role skills
B.) The maps never required any change as drastic as what is being experienced(a bit off topic but still worth mentioning)
C.) Any issues with a certain class (drg piercing talon, which wasnt that big of an issue, or healers having too much healing) could have been fixed with a simple potency reduction, instead any change to class or its abilities is now more difficult to balance considering they have more than one effect and requires a change in other abilities to compensate.
D.) If the Devs spent as much time on SHB pvp as they are now or instead of developing CC or holding off untill the former issues were resolved then most problems would've been solved by now (the main cause of the problems)
E.) I'm not a healer main so I can't comment on whether the value of a healer in the current pvp is diminished or not but I can say going as tank in shb FL I enjoyed my role as well as the healers that could rescue me, I don't see why a large-scale mode shouldn't incorporate more of the trinity system considering any issues wouldve been easier to resolve, while it's anecdotal ive been in matches with an entire healer alliance and still lost.
2.) EW CC is the best version of small-scale pvp despite not knowing how it would've worked with feast (TDM)
A.) Ques are faster, whether this is due to the battle pass or the removal of role restrictions is uncertain.
B.) Roles are not as impactful towards achieving a win, despite certain role classes being somewhat more advantageous than others (war vs pld, whm vs sch , mnk vs every dps, except drg maybe, ect)
C.) Classes are beyond unique and interesting, even though they're screwing up the management
3.) RW, idk as I rarely play it but should be added to daily roulette challenge, not relevant but needs to be said
The only solutions I can think of is to separate large-scale and small-scale toolkit, however this will never happen or a Separate FL mode(s) with smaller numbers (I'm not too convinced this will work)