I'll play. I play because of nostalgia, pretend, being creative. Those are all really good answers and they all fit.
I started Mu*ing back in 1994, on Gemstone while I was still in high school. I was into tabletop RP in college and Mushes were a natural extension of a "sometimes" thing I enjoyed. I never got into WoD because, my TT group was mainly a D&D Shadowrun group. College had to end eventually and real life(and a kid) set in. So I gradually stopped.
While in college, I minored in theater. So yeah, I've always kinda been an attention whore and had a weird enjoyment of being other people. Mu* always kinda scratches that itch. I can think up an entire character background and description in minutes. Yeah, I even have an alter ego like Beyoncé in real life (let's keep that between us).
I've always been kind of arty. I went to a technical high school and did graphic design. I was the girl in the back of the class drawing instead of daydreaming. While I don't write creatively, I do play around with it and I even have a dream book--that I actually use. This just seems like a hobby for someone like me. I'll probably be doing it off and on until I'm an old lady.
Why don't I play? The simple answer is real life. When I graduated, I became a teacher. Those first couple years as a new teacher are intense. I just didn't have time to do it. Then it turned into having a baby, which rapidly devolved into single motherhood. But now my son's a preteen and doesn't require(or want)as much of my time, but I got married and I have a new big baby to take up my time. Along with football practice and basketball practice, plus work....well, this hobby takes a backseat a lot.
So often I envy the people that have a lot of time to sink into Mu*ing. I only have a sliver of time to put into it and most of the time it's really late at night, so even when I get into it again, it doesn't feel like it's worth my time like it used to. That and I don't bounce back from staying up late like I used to. So I play for a little while, then I pull out because it kind of becomes a little much.