Because blizzard failed pretty badly at initial class balance in vanilla. As evidenced by them having to a class review of every class in vanilla, read that again, every class not just hybrids.
In the case of hybrids part of those class reviews were to make their non healing specs more viable.
Because blizzard was still trying balance them with utility in BC, and while it kind of worked(hybrids were more welcome as non healers than in vanilla) it didn’t quite bring them up to par. By wrath hybrids were fine.
Yes that is indeed the case, we know they clearly failed with their initial class designs as every class got a review in vanilla.
In the case of hybrids part of that review was aimed at making non healing specs more viable.
And yes it took until wrath for them to give up on the utility instead of just dps balancing as it wasn’t working. And BTW wrath was old talent trees and pre any pruning so long before homogenization started.
Changing a character’s talent build is called respeccing or is referred to as a respec. Characters can unlearn all of their talents (becoming untalented) at their respective class trainers, at a cost. Unlearning talents scales up the more times it is done: 1 gold, 5 gold, 10 gold, 15 gold, etc., up to 50 gold.
The cost to unlearn talents decays over time. This cost will be reduced by a rate of 5 gold per month to a minimum of 10 gold.