I'm not talking attack speed, just the missile speed. Turrets, among having so many other issues, are so easy to game. You can jump in and out of turret range before the turret can acquire you. Champions with invulnerabilities have a huge margin of error when dodging shots.
Increasing the projectile speed and make the attack animation fire faster.** It won't change the turret's DPS at all**; it'll just make it so people can't game them so easily.