You may want to hit it longer, but it helps to keep it in play, you can be long in the lake or trees and that does you no good either, you would be better off a little shorter but in play.
It gets tougher the longer you hit it out there, think of it like a fan spread out.
Near the centre of the fan, all the vanes are close together but as you trace the vanes outwards they get further apart.
The further offline your shots are the wider they will be the longer they go.
 In other words to hit a fairway 30yards wide at 270 yards is a lot harder and requires more accuracy than hitting it at 200 yards.
There are only 2 ways to hit the ball longer and straighter in the golf swing motion off the tee: 1.
Increase the speed of the clubface at impact 2.
Strike the ball at a squarer angle.
There are many ways to improve both of these, but they are the only two things that make any difference as to how far the ball eventually goes.
Get them both right and the ball is one for one huge ride, break out the binoculars! Trying to hit the ball harder does not work in speeding up the clubface because what tends to happen is that everything goes out of sync.
Every now and again it all clicks in place but probably no more than 1 in 20 shots.
If you try and hit it harder with the hands or arms, you leave the body behind which will actually slow the clubface down before impact.
Like wise if you move the legs faster, that will leave the hands and clubface too far behind.
  Think of it like pushing a car.
Try doing it on your own and it's not easy but if there 10 of you then it's easy, even uphill! If one muscle in your body is hitting at the ball that would be a lot slower than if you had 10 or more.
Co-ordination and having all the elements of the swing work together will be a lot more effective.
The perfect impact position would be for the clubface to strike the ball exactly square or at right angles to the target with the club travelling horizontally or slightly on the upswing.
What stops the ball going so far is spin in the wrong direction, some backspin is needed to keep the ball airborne, but too much and it will climb upwards and not go forwards.
Any side spin will make the ball curve to the left or right and reduce distance.
There are a lot of permutations, it's not easy! So those are the points to work on if you want to drive the ball longer off the tee and get your golf swing motion correct.
Now the next is question is how to start working on these in your swing to actually get that extra yardage you need.