It's funny that you mention fire giants as where your role began - it's where mine ended.
I pulled in crushbone. I pulled in perma. I pulled in sola. I pulled in solb. I pulled in lguk. I pulled to the efreeti. I pulled everywhere...until fire giants.
I pulled using lament. It's not particularly reliable (especially on high level mobs), and sometimes I'd be forced to pull back more than one, but it worked fairly well until FG's. FG's are flagged melee range casting only. They are impossible to lament.
Your role began because my role ended. Pulling is crowd control. I can either eliminate mobs from the fight by not pulling them, or eliminate mobs from the fight using mes/charm/fear. Either way, that's my role - I eliminate mobs from the fight.
Then came monks. Monks suddenly became not only good at CC - but the best at it. Better than bards. Better than enchanters. Better than the classes whose primary role is crowd control. Monks stole our ability.
Yes, it's been this way for some time. But that doesn't make it right. Necros were the primary damage dealing class for some time, and they were fixed - because it didn't fit with their intended role. My necro is now dead to me, because while its intended role works flawlessly (solo), the role I picked it for does not (superior [admittedly unbalanced] raid damage).
At this point I don't expect to see monk FD nerfed. I would just like to see bard/enc CC raised to the same level as monks. If a monk can remove a level 75 mob from a fight, well so should a bard/enc. If a bard/enc can't remove a level 75 mob from a fight, well then, neither should a monk.
Bards have always done CC partially through pulling, and partially through in-group mes/charm/fear. If any class should be #1 in the area of pulling, it should be bards. Again, I don't expect this to happen, because monks would be upset. Monks were never intended to be a CC class. Monks were never intended to be gods, #1 in multiple roles. But they are, and there's little likelyhood of it changing. In one role, the role of pulling, bards should at least be just as good.
Let the puller, be it bard, monk, or SK, be decided on the basis of skill, not just by class. Currently on live servers, if I need to have some mobs split, I have a monk do it. Even if the monk has no pulling experience, no skill, and no knowledge of the area, while I have it all - I still have a monk do it. I tell the monk what to do, step by step, like a puppet, but it's still the monk that does it. When the monk finally pulls mobs to the group, I rarely can do anything with them. I certainly can't charm or fear them, because those abilities cap at 51 and 53 respectively. Occasionally, I can mes one of the easy ones. Is this my role? The monk eliminates a dozen red mobs, and I eliminate one blue one?
If you think your role will be gimped in PoP, consider that your role is mine, and was never yours to begin with. My role was stolen, and has been further gimped in one way or another with every expansion (high MR mobs that always resist lull in Velious, and immune to lull [due to harmony] mobs in Luclin).
While you may not like being forced into the role of damage dealer, consider this: it's better than the role of mana battery or AFK buffer, and that's what your role theft has reduced bards and enchanters to.
You've said it yourself - pulling is an active ability. Manasong is a passive one. Damage dealer at least isn't a pure support class. It's the active to support change that has bards and enchanters unhappy. Both picked their class to CC, and CC is an active, primary role. Both classes are forced into support roles on raids.
All the frustration you fear you will experience, and more, we've been experiencing for years. We've been experiencing this frustration because monks have stolen our abilities and claimed them as their own. With FD gimping in PoP unlikely, yet high level mobs assured, our roles are still clearly removed in deference to your stolen one. It's hard to feel even a small amount of pity. Monks feel none for us.