While speed is a favorable thing with any serve, don't forget that it is the action of the kick serve, the arc, the bounce and the angle which the kick can be hit to the ad court especially, that makes this serve effective too.
Like a curve ball in baseball that his thrown too hard, there will be minimal break. If you lean in too much and drive your kick serve, you will have a fast serve, absolutely, but you will lose some of the dynamics that the kick serve done at the right speed would have.
Certainly, increasing racquet head speed is the key to any great serve. This aspect will increase the action of any spin or flatter serve. But, don't confuse velocity of the ball with the combination of maximum ball rotation with ideal serve velocity.
Good luck in achieving both!