I must admit I never had a gaming mouse until a few years ago as I thought it would barely make a difference. However after trying one of my mates I made myself a believer and bought one the next day.. never looked back.
What makes them great for gaming is the higher DPI and faster polling rate, it makes everything feel much smoother and more precise. Those long range headshots you would use to struggle to maintain on a crappy mouse are made easier, especially in conjunction with a proper gaming mouse pad.
You right, it wont make you a better gamer, but it'll definitely help.
Man I sound like a sales rep D: