One of the reasons I like playing bass is that, as a general rule for the music I like, there is someone between me and the crowd, ie: the guitarist/singer. Not being the centre of attention yet being a key part of the performance is what I seek.
I don't do well in crowds unless I am occupied with a task such as bass. I see the singing bassist being a stage in my development that will help overcome some of my lifelong fears with regard to crowds and crowd behaviour in particular. That's my ultimate aim. It means I must make mine an impeccable groove, as mentioned by MK in a song a long time ago.
Without going into detail, my upbringing has turned me out as a confirmed loner. It's not good for me in the long run so I have to make extra effort to keep in touch with the living, as it were.
It doesn't matter whether you are on-stage or in the mosh-pit, music is a great ice breaker.