In my limited experience, any game that concerns itself primarily with combat options and cool abilities, and has combats that take more than thirty minutes to resolve limits roleplaying.
Any time you have to base your character concept around making choices between combat abilities, roleplaying will suffer. Games like OD&D, BXCMI, and maybe even AD&D1e before Dungeoneer's and Wilderness Survival Guides did not hamper roleplaying because how you roleplayed differentiated your character from another of the same class, not your different abilities; you didn't have any. Take for instance a 9th-level fighter in any of the above games. Mechanically speaking, the only differences between any of them would be gear and ability scores. You had no major choices to make (except weapon choice.) The exception being magic-users and clerics with spell choices. All of these characters were frameworks around which you would build a persona.
In third and fourth edition, characters are defined by what they can do in combat since that is where the focus of their abilities are. Granted there are skill resolution systems in both editions that cover out of combat actions, but there is no doubt in my mind where the focus of D&D has always tried to be (2nd edition being the odd-man-out.) I think the more decisions one has to make about choosing a character's combat abilities, the more likely one is to think of their character with respects to their combat ability.
I just wonder if "roleplaying" got its start from the early players getting tired of playing the same 9th-level fighter.