... Besides, I'm not paying a monthly fee (optional or otherwise) for a single player game or paying for microtransactions in a single player game.
I'm happy with the games I have: Skyrim, Morrowind, Fallouts 3 and NV, etc (I'd count oblivion, but I can't get it to run with Steam+OBSE+Mod Organizer). I just don't need anything else ATM.
I DO NOT judge ESO by the beta I played. However, while I was patient with the bugs I encountered (it was a beta test after all), something just didn't feel right to me while playing. I couldn't put my finger on it.
That said, I still plan to get ESO soon. When I do, I can only envision playing solo. One, I have zero patience for seeing multiple players jumping around like idiots and crowding certain areas and NPC quest-givers. Hopefully I will discover, as Phil stated, that things will open up for me once I get beyond the starting areas. Two, I do not have time to play the game with large groups or player guilds. As I do now with any stand-alone game, I play when I can play. I would be doing my large group a disservice by not being able to accomodate the group's schedule. With that said, I can see grouping up with a few players from the Vault to tackle a dungeon or two every now and then. It would be nice to continue the tight community of friends I have here on ESO.
I mainly want to explore and be immersed in lore.