The double pick up (Humbucker) gives you a more full thick sound compared to a Single coil, both kind of pickups are usefull for many purposes there's not such thing as useless on this matter, that only depends on your style of music you wanna play.
If you are into a powerfull round full sound, humbucker on bridge position it's your bag... maybe later you can get a higher output pick up for more edge and punch on your sound (high output pickups are used alot by guy like Dimebag Darrel, Zack Wilde and many other metalheads).
Make a little research on DiMarzio, Seymur Duncan, EMG or any other manufacturer website so you can have a clear vision of the market offers.
And try all the pick ups on you next guitar... it's fun, I love the sound of a badass humbucker over a big distortion... (chag chag chag ca chaaaaaaaaaan) it's great but, experiment... you may find something you like besides that tone.
Power corrupts. Absolute power is kinda neat.