I miss her locks too; big, beautiful, long, and not like everyone else's (long hair with dramatic bangs or side swept.) It was pretty basic but girl had good healthy luscious hair.
I think she cut it to probably rejuvenate herself. It's not like she did it for a lakorn role, she's wearing extensions in mongkut saeng jun. She's had long hair for a while too, and the end of 2008 was tough for her. My guess would be that she cut it to kinda cleanse herself in some way. You know when you cut your hair, don't you feel somewhat new and improved, granted that the cut is good ^_^