From a player perspective, I prefer them since I am willful and selfish with my time, whilst simultaneously lacking any of the necessary faculties to draw people under 'my banner'.
In character terms, my Minmatar is caught up in family and personal matters, focused more on what others feel she should be doing than what she wants to do. I've considered following in Arnulf's footsteps with her, creating a public face for her clan, but she hasn't earned the respect among her people for that to make any sense IC.
Shiki has also considered striking out on her own, but that would mean shifting from research to administrative duties, spending far too much time trying to secure funding and making sure all the red tape is neatly arranged while missing out on making real scientific progress. She'd rather pay her tax to the Corp and let them worry about the overhead so she can focus on her passion.
So yeah, I'm in favor of the one-member shell corp and have characters perfectly suited to not being in one.