This is a weird stance to take.
Numbers aren't the be all end all, sure. But there's a difference between, "This person is doing more damage than me all the time," and "This person's class outclasses everything I do in every single way, while having more variance and variety than I ever will."
Class aesthetics are a big part of why people play certain things, especially stick with them when they're in a sorry state. But the feel of a class in various different game modes is just as important to pay attention to. When you're playing a game and your favorite class is awful or left behind in regard to other classes in the game, aesthetics isn't going to do much to keep you wanting to play when the gameplay isn't there to back it up.
I don't care about how other people are doing in comparison to me in terms of DPS, but when a class goes into WvW, sPvP, and PvE and is essentially a lesser version of other classes and it's incredibly noticeable in its core gameplay, then that's an issue.
Do the mechanics feel good in comparison? Does the class have as many tools as other classes? Are there as many options available to the class as other classes? The answer to these, when you're comparing warrior, is obviously no. So, people are rightfully disillusioned and disappointed with its state in the current iteration of the game.
No one likes when their favorite thing to play gets stomped by other classes with modernized designs, because it becomes less of a player skill issue and more of a systemic issue that only the devs can fix. Numbers are just a small part of the puzzle. Mechanics, variety, gameplay, aesthetics, and general feel are just as important and there are many more places where Warrior is lacking than in just DPS numbers.