I'd still argue that it wasn't very interesting and it just didn't feel great if you had invest talents into support talent that didn't exactly stack well.
Take Windrush Totem on Live for example, if you have multiple Shaman, you have multiple totems, which is great because they stack just fine.
If you had instead of Windrush totem a "deal x% more damage" Totem (which doesn't stack), you would have to check whether another Shaman is present, make up with him / her who select the damage totem and who doesn't.
That a serious question?
Did you have to manage Astral Power, Soul shards (the ones that consumed for actual useable damage abilities)?
Were there any procs out to watch for?
Did you ever ask yourself: "Maybe i should play Talent X on that fight" during Classic?
Like, do really want to on record and say that you don't notice any difference between the MoP - BfA era and classic regarding (class) gameplay?
The big question is why?
Why would you suddenly decide to, nah fuck it, i want to cast some Fireballs instead of Frostbolts?
If i have invested quite a lot of talentpoints into an ability, why would i also put talentpoints into another that directly competes with this ability?
Like, if i wanted to apply a slow, okay, reasonable argument, but then i could just use Frostbolt Rank 1 or Cone of Cold without investing 5 or more talentpoints into an ability that is due previously spent talentpoints not that useful by comparison.
It's not you suddenly get some proc that makes Frostbolt better or something, it's you suddenly going into a different direction entirely without reason.
Even if you want to argue over something like Resistance (meaning Fire Elementals), then it was simply a wise choice to move your talentpoints into that tree that avoids this issue entirely.
You essentially gimp your character for no reason, this is by no means a "raider" thing, but simply how it worked on literally any level.
Just to give an example where i am coming from, if someone plays Frost, but has Improved Blizzard selected, because he wants to do some AoE farming afterwards, that's fine to me, then he's marginally worse, but has some of them few impactful abilities in Vanilla instead to do something cool, that's fine with me.
But if i see someone that plays fire, but then suddenly puts five points into Imp. Frostbolt, (if talent inspection were a thing) i struggle to think off a rational solution.
"Because i want to" is in my opinion simply not a great explanation, one should at least put it into words what they like about it.
Things like that weren't not really great costumization, it was just a red flag for other people.
In my opinion, it would be a wiser choice to actually push forward and make clear you want some "Frostfire Mage" (if that's your fantasy) rather than ask for system that you want to use you in a way that wasn't even intended to be used that way in the first place.
And that's just kinda the question whether you used those abilities.
Once you're deep into Fire, you're not going to use Arcane Missiles or Arcane Blast (from TBC and onwards) outside of fringe situations, because it's just strictly worse than Fireball.
Similiar thing for hybrid, okay i got more healing spells, what now?
Are those abilities actually effective? From TBC and onwards, hardly, because as talent trees grew bigger, so did the difference between specialized abilities and non specialized.
Second, do those abilities actually support my role? If i'm a Shaman, having access to Chain Heal, Healing Rain, both lesser and greater healing wave is nice...but doesn't really help me accomplish what i want to do if i'm Ele or Enhance.
This is where it all loops back to the point that these additional barely mattered anymore if those specs did not have a lot of common ground to stand on.