One advantage d20 (and linear RNGs in general, especially d100) has is that it's dead easy to calculate success probabilities. What's the highest number you fail on? Multiply that by 5 and that's your probability of failure. There's no similarly-easy trick for 2d10 or 3d6, though they're not too bad to do offhand. Dicepools are easy to calculate average successes for, but figuring out the probability of "x or more hits" for non-trivial x is something very few people even know how to do without looking it up. I don't even remember what the formula for expected value on roll-and-keep is.