I know this is an older post, but thought I'd register my thoughts, since "RPGs" are the types of games I play the most, going back to the 1980s.
Yeah, I'm an old-school gamer (well, just old too). Game definitions used to be more clearly defined years ago, and as DXCHASE said, those lines have become blurred. If someone wants to call RD2 or any of the AC games RPGs, I won't say they're wrong. It really comes down to personal opinion and feelings. Those games aren't RPGs to me, but that's only my opinion, it doesn't make it fact.
I remember playing the Half Life games, and totally consumed in my role as Gordon Freeman. Those games changed how we looked at Shooters, giving us a real story to drive the games forward. There were no "Stats" to level up, no choices to make, and the HL games were pretty much on rails, going from act to act. But I assumed my persona of Gordon Freeman. Does that make it an RPG? Not in my opinion, even though I played a role as the main character.
Then there are Action RPGs (ARPGs), games like Diablo 1 & 2, Sacred 1 & 2, Dungeon Siege, Grim Dawn, ect. Those games had stats, leveling up, loot galore, but minimal story and very few choices that mattered or changed the outcome. Combat, leveling, and loot were the focus. Does that make them RPGs? Yes & No to me, ARPG (as opposed to RPG) is a pretty good classification.
My personal definition of an RPG is a game with a story. Could be single character, or party based. The game has some type of "leveling up" system, where you can improve your stats and/or abilities, preferably with the options of building a character in multiple directions. The story should be the main focus, and the choices (there should always be multiple choices) you make should affect different outcomes in the game; either in the world itself, or in peoples lives, as well as the end game.
Again, all these lines of definition are blurred nowadays, so it comes down to your own perspective. In essence, there is no "true" definition of an RPG today.
Okay... then level-up system AND turn-based.
What about Real Time with Pause? Many games considered RPGs use that mechanic.
It seems most people define an RPG on how fantasy related the game is. If it doesn't have wizards or orcs or dwarfs, its not an RPG.
I think what makes a game an RPG is so blurred nowadays.
What about Fallout 1 & 2?
I think what makes a game an RPG is so blurred nowadays.
And you hit the issue exactly, saying that the definition of an RPG is blurred, maybe more so than other genres.