It's not the first or last time ppl call warriors op when they are just good/viable. Warriors are so often trash, that ppl get used to it
I haven't played on the PTR yet, so I can't say for myself if warriors are OP, balanced or still in need of buffs, but I think that I can see where all the hate about warriors (and most other meeles) come from as soon as they are in a good spot.
When it comes to meeles overall, their way of scoring kills makes people react. Up until a certain level, people does not know enough about the game to properly peel, which makes melees cds incredibly scary (I am one of those people, so I'm not trying to be elitist or anything). This means that up to a certain rating, going into an arena and pop all cds off the bat is a successful strategy which takes a lot less skill to execute than it takes to counter. This (understandably) makes people react and ask for the nerf of said meele.
Therefore you will see a lot of middle to semi high rated people complain as soon as a meele is good, but when looking at ladders, they are not doing as well since the high rated teams knows how to peel them properly. Imo it is kind of a design flaw that I would like to see fixed somehow (I have no idea how) to the next expansion