You're just using it wrong. And don't let anyone try and tell you there's only one way to play a ranger in PvP (poison everyone, etc.) Try different things, play other classes to learn their strengths and weaknesses, and realize that you might have to drop wilderness survival to get anything done. You might feel a little insecure about not having troll unguent or storm chaser so you can run around and annoy people after the battle's been decided, but that's tough cookies. This is not to say that wilderness survival is useless; in fact, it's one of the better attribs for bastardly ranger tricks. But sometimes you need to fill a different role.
If you're serious about using a pet, you need to have a lot of pet skills. I run with 5
minimum, and often throw in a 6th. The pet can do things twice as good for half the energy cost, so why keep personal skills when your pet can do nearly everything for you? Also, treat beast mastery just like marksmanship. Do you ever leave home without your marksmanship attrib below 12? I should hope not. Beast mastery affects your pet's base damage, which is equivalent to a max damage bow (15-28 @~2s refire). I promise that if you toss in ferocious strike (the elite pet attack) and pump your beast mastery to around 15 or 16, you'll see results, just like you would if you pumped any other stat to 15+.
Pets are how rangers achieve the damage of other classes. If you have a pet, and your beast mastery matches your marksmanship score, you are basically doing
double your normal base damage. Now throw in ferocious strike to feed your energy reserves and you can spam massive power attacks with both bow and pet until you get tired of it. In PvP, be sure to bring along pin down and/or the pet cripple attack to prevent people from running away from the pet. In fact, why don't you just look at
this build which I end up linking to in every ranger complaint thread to show how to build a ranger that can't be ignored. It still takes people by surprise in arenas; no one expects the pet to hit so hard, because so many amateur rangers use their pet as an ineffective meat shield. No one expects the pet to be nearly impossible to kill, because I heal him for 104 every second and he gives me the energy to spam it repeatedly.
Beast mastery is not useless by far. It's just misused.