I think you're right, my hair used to be as tightly curled as Keri's when i was younger but after years of brushing, hairdye and cutting my hair in different styles, it changed a lot. It has changed a lot after i went CG too, my curls are finally starting to come back.
It defenitely looks like she had started the CG method too, her hair looks a lot more shiny and healthy with much less frizz.
It's the volume that's been reduced after her big chop.
But her hair looks a lot more healthy now than it did in season one for instance.
Hopefully she'll start wearing her curls more often again, she's an amazing actress with a great personality and a beautiful complexion, it's a shame the stylist (or maybe just she) is trying to change that.