Well you got the point :)
It has been popular because it was an easy way to increase what a player can do when you are limited technically. Even now, you can't always have a player skill based action for everything. How do you know if you succeed in a surgery? If your character is able to lift a rock or a boulder ?
As for D&D, people like it because you are only limited by the collective imagination. A game is a different media, you can't really compare.
Even on starcraft, you can hardly find more skill in a game, units have a chance to dodge hits when shot from lower ground :) League of legends also has random elements.
By enforcing skill based action only, what a player can do is limited by the work of the developpers. RPG fun does not come from rolling a dice to perform an action but to be able to choose what action to perform at what time.