You can take a look at my armory. You'll see !@#$ty arena ratings, no rated battlegrounds, unenchanted items, no PVP weapons...I forgot what I was talking about.
I've gotten pretty frustrated at my class. Sometimes I've even considered rerolling. But I won't. Because I love my class. And that's what's most important. Sure, we can't faceroll like we used to (didn't play Cata, but to my understanding, rogues were dominant), but no class is completely useless.
I've seen rogues at the top of damage, and I've seen myself get super pissed because I can't seem to do well. But I'm still learning my class. And every day, it gets better. Not because of my gear, but because I'm trying to achieve mastery of the class. Mastery of the class is not impossible. It is more difficult than other classes, but I don't think that rogues are completely and utterly useless. It just takes more time to master, which I would much rather have than a class that pops a one shot macro and wrecks everyone with ease.
Once again, I don't claim to be a good rogue. But I feel like I'm getting better. I have a lot of work cut out for me, but I love my class, and I'm going to stick to it. I'm gonna keep gutting it out, get my weapons, and hopefully make people just as frustrated as they made me.
Take a deep breath, love your class, and look at it as something you need to work up to rather than have it handed to you.