The more fiber you eat, the more your body becomes used to it so if you stop, you'll get constipated where you wouldn't have before. So yes, even fiber can create a dependency.

Instead of shooting for 25-30g, how about going by how you feel? Do you go regularly enough to feel good?

I gave up counting fiber grams and just go by how I feel. I always tell people I know if I'm getting enough or not.