I think our definitions of “interesting” may differ. If we take the angle of hobbies, for instance...
I would say that picking up running as a hobby can provide many social benefits. It’s relatively popular, it’s virtually omnipresent, it’s considered by many to be a ‘morally superior’ activity, it’s likely to make you more attractive in the dating department.
But I wouldn’t really call a person interesting only due to having running as a hobby, nor do I consider running an interesting hobby.
Most people, on average, haven’t had too many experiences or interesting hobbies by virtue of being the average, but I haven’t found that the average person has issues socializing. I’m not sure if being interesting is really all that related to that.
But most people are not going to be ‘very successful’, and I am going to automatically assume that this is not included, since it’s often statistically exclusionary (only a few people in the entire world can be olympic level sprinters).
It is most certainly not required to be ‘great’ to be socially successful, or, for that matter, interesting. As for my opinion of the whole ‘greatness’ chase, see here: http://lesswrong.com/lw/mmu/how_to_learn_a_new_area_x_that_you_have_no_idea/cu3o