A drink is easier to deal with while riding then trying to take pills out of your pocket, count them out and put them into your mouth, and the electrolytes absorb faster into your system when already in solution. Those are the reasons for me. If you stop a lot, not a big deal for the first point, but also in drink form, you're constantly giving yourself a small amout of electrolytes instead of bombing your body with a big dose every x minutes. Main good points for the pills in my mind are that they don't go bad in heat in your pockets, and if you're riding somewhere where there is no Gatorade, etc. to refill, you have a portable solution.