Roleplaying is about making a character that is seperate from the roleplayer. The roleplayer and the character are two separate entities, even if the roleplayer is roleplaying as himself. The character that the roleplayer designs is human in his abilities. He cannot master every skill. He cannot do everything.
The skills and stats systems were, as a concept, was designed as a way to represent the abilities of the character as a whole. Where he succeeds, and where he falls short. He can be a good swordsman, but fail as a negotiator. He can be a good smithy, but fail as a tailor.
So let's take Stephen Hawking and Michael Jordan. Stephen Hawking, is good at quantum physics, but bad at basketball. Michael Jordan is good at basketball, but not at quantum physics. Stephen Hawking may roleplay as Michael Jordan, but since the character is Michael Jordan then he is limited to what Michael Jordan can do. Vice Versa.
This.
shdowhuntt60 is among the few who actually understand the difference between RPG and non-RPG.
That is the main requirement to have a RPG, separation between Player and Character. the player can decide what the Character may do, but not how well will be done, be it hit a target, block an attack or persuade a NPC. Only the character can perform those action and the final result is only determined by the character skills. So, Morrowind (or Daggerfall) is A LOT more RPG than Oblivion, and maybe OB is not a RPG at all.
All the rest (stats, perks, exploration, interaction with NPC) is not needed to define a game as a RPG, but it helps to have a better RPG experience.
In my opinion, a great RPg must have a great character customization and development. Maybe perks could help, but skills are diminishing more and more (DF 36, SK 18, this may limit customization, but there are perks so, we will see). And, general attributes like strenght, agility, intelligence, gone? How can I define my char in general? By the skills?
Second, Interaction with the world, and action and reaction concept. I think that we can sleep well thinking about what will be in Skyrim.
Third, possibility to build a life or a career. Morrowind had a lot of factions, for example, Oblivion had only few. That did limit replayability for OB, at least if you wanted to make different quests with different characters.
Forth, Class limitations. A warrior has not the talent of magic, a mage will be severely disadvantaged with an armor. This also help immersion with your character. (If there arent limitations made by the game, the player may create them as he wishes, so it's not really a problem)
Based on this information, will Skyrim be a RPG? Probably NOT, but a great adventure game, yes that's for sure.