been there
I started OCS late Sep 2007. I got 10 inches cut before going... thinking ... okay, they'll trim a little and I'll be good to go. On the second day of OCS, I sat down in the chair, the woman quietly said, "I'm sorry." And she took the clippers and went at it. She buzzed the sides and left me about an inch and a half on top.
After talking to some of my classmates, the only reasoning we could come up with is that they try to de-feminize you as much as possible. You're not allowed to wear make-up or jewelry... no perfume and obviously no dresses or skirts. After the initial haircut, it's up to your DI's. If your DI "advises" you to get another cut... you better be at the NEX as soon as possible. I got a couple cuts at OCS to avoid any "confrontations", then talked to my DI about it during candio-phase. He said, "It's a damn shame what they did to your hair." If only I'd had known!!!!! Again, it just depends on your DI/class officer/class chief. But yes, everyone gets a hair cut. Just be glad they don't shave it! And it is SO MUCH easier to maintain!! (but I'm still bitter.)