For the first question, why I wear lolita, can I be facetious and just answer this with "Why not"?
As I mentioned a bit in my Lolita 52 post about my lolita lifestyle I've always had a wardrobe segmented into normal or everyday clothes and my dress up clothes for when I felt like being more out there. Lolita is the first fashion style that I've loved enough to actually stick with as my dress up fashion. That's the short answer, really; I wear it because I like it.
My cat, however, doesn't like posing with me much ^__^
Also, as I've said before, lolita makes for good, easy photoshoot outfits!
And, also, having a petticoat on is like having a personal forcefield. It makes me feel powerful ^__^
As for the second question, why don't I wear lolita more often, the answer is kind of evident above as well; lolita is dress up clothes for me. I still consider it a fashion, but for me it's not one I'm interested in wearing everyday. Mostly I wear it to uni some days and when I'm going out somewhere and feel like it. But I don't go out much and uni is only 2-3 days a week for the duration of the semester so my opportunities are fairly limited. I do wear it a lot for photoshoots too, which is great, but overall my lifestyle doesn't really suit lolita that well and I'm not willing to force myself into impractical clothes just for the sake of it; and by wearing lolita only when it feels right and not trying to force it as an everyday fashion means that wearing it is always fun and special for me.
Besides, wearing my blue velour tracksuit [and the similarly comfortable things that comprise a lot of my lazy-day clothes, I do love my colourful work-out wear] is special and fun in it's own way. After all, it's real velour...