I got two entire years' worth of gameplay doing quests entirely solo.

The fallacy here is that you have to do all of the content. If you don't want to be "forced" into a group, don't worry about doing dungeons. There's no point to doing them anyway, because you're not going to need particular set items to handle basic overland content (of which there is a ton, I say again).

If you're so solo-minded that you can't even feel comfortable asking for help to defeat a world boss, pass it by. You don't need its drops.

I just refuse to accept that this game can't appeal to players who want to play the game entirely solo. It has more quests and diversions suitable for a single player than any of the games since Daggerfall, plus the option of joining up with other players and having fun in group content! You might surprise yourself with how much fun you have doing a good dungeon.