Real RPG's are not that difficult to define, as once again I will repeat what Todd Howard thinks:
"I think that character development is the core element that drives any RPG (what I call a 'real' RPG today, because of all the fakes!), and always will be. You do need a good story, or a good world, in which to use that character, but the first thing to get right is the character development."
Character development. In Fallout 1 and 2, a 100 perks and skills for your character. Hence an RPG. Mass Effect gives you three pre-made characters with most stats in the weapons and armour.
Based on Todd Howard and me then, Fallout 1 is an RPG because it has character development, and Mass Effect isn't because it doesn't.
If you want to see confusion, just go and see that GOG calls Two Worlds an Action RPG when it has as many character stats/attributes as Oblivion or The Witcher, which are both called RPG's! If GOG is confused and if many gamers are confused today, when they weren't 10-15 years ago, I would say the RPG genre is going to shortly disappear. When you see Bioware go from Baldur's Gate and Planescape Torment to Jade Empire and Mass Effect, that's another sign of how 'real' RPG's are disappearing. The next Elder Scrolls game is rumoured to be an MMO, and Obsidian (of Fallout 1 and 2 fame) have a Mass Effect style espionage game that they describe as 'an RPG with 25 hours gameplay'. An RPG with 25 hours gameplay? Isn't that an oxymoron......?!