I never Mod. I play Morrowind, oblivion, and Skyrim 100% Mod-free. Wouldn't play any other way.
I can understand if you are on console, however, if you are not....
The only one you are depriving is yourself. But, please, don't let me try to convince you. Modding and the immense enjoyment is something people will have to discover for themselves.
For me, in Oblivion I played a game with a house of my own manufacture in every town, that was suited to my playing style. New towns, that I actually built myself that added five more complete locations to the world, tailored to my taste with characters I created. I spent a few weeks working my way through The Lost Spires, added an incredible companion that felt so real, Vilja. Played with graphics far above and beyond the Bethesda made ones, Qarl's Texture Pack. Used a female body model that was far more realistic and didn't have ugly seams, Robert's Female Body model. Enjoyed weather sounds in all exterior cells and gazing out windows with Immersive Interiors. The list goes on and on....Morrowind and Oblivion with mods was a whole different and far better game that I played for years and years. I didn't play it and get tired and plonk that game back on the shelf when bored as would be the case with vanilla Morrowind and Oblivion, when you have seen it all, that is all there is to do and see. The games just kept getting new content and better content and that was priceless.
Skyrim will be the same....and even better. As a modder I can see that the basics for some incredible mods that go far and beyond anything done in an Elder Scrolls game, are already there. Just waiting to be expanded on.