I personally think the normal dungeons you have to do in story mode are already very easy, especially now that they are outdated. You sometimes have to dodge stuff or target another enemy than the boss but that's usually it. There are other RPGs that are single player and have harder dungeons and bosses.
The solo duties like job quests and story instances are often even harder than the dungeons. ;D

I'm very shy and introverted and communicating with other players is a little difficult for me. While not being forced to play with others sounds nice to someone like me, I still believe that being able to solo everything in an MMO is somehow wrong. I really get where you're coming from, but the content you're forced to do with other players during the story is already easy enough even for less skilled players. It's even so extremely easy that less skilled players don't get better just by doing a normal dungeon because they don't even have to try.