I Implore people to consider any game with that much range. The limits of the Roleplaying in any ES game is only up to your inner child.
And i would be hard pressed to see Skyrim as anything other than an RPG.
Anyone who would say Skyrim is NOT an RPG wouldn't be worth arguing with.
As far as the range of ES games, you must be relatively new to RPGs?
The father of all PC RPGs is still the Ultima series which spanned a time-line of approximately 20 years of successful PC RPG invention, success, and domination. The very terms, "open world", "non-linear", and "seamless map" were invented by the Ultima team. I can also tell you that when I was first introduced to the ES series I felt it was a diluted and streamlined form of PC RPG because of my experience with the Ultima series.
These days however, for a modern game with modern graphics I will say Skyrim is in the lead for bringing all of the great, PC RPG elements to the table.