The mix of player skill and character skill is a defining element of an RPG. In an RPG, you are playing one or more characters Ė characters who have defined (but dynamic) abilities and limitations that change over time as you make progress through the game.
If success is principally dictated by your actions and skill as a player, then itís not an RPG. So if your character is supposed to be a mediocre shot, but as a player you are lining up and endless stream of head-shots for critical hits, then chances are that at least that aspect of the game is really not very RPG-ish. An RPG may blend the two elements by making your hits based on player skill and your damage based on character skill to try and strike a balance, which may satisfy many players. But there has to be some kind of cooperative give-and-take going where the actions (and skills) of the player are filtered by the characterís abilities and limitations.
These days, thatís a really, really fuzzy area, and not much of a dividing line. Are better weapons and armor an attribute of your character? Many games include ďRPG elementsĒ including some kind of upgrade mechanic. Itís not a hard-and-fast delineation. Itís a spectrum.
On the flip side, a game canít be all about character skill either, or itís not a game. Itís Progress Quest.