Fabricating claims at this cost is simply uneconomical. Yes, I have a big income, but what the heck, I could just revoke that county off of the holder and eat the penalty. Fabricating is a better tool at low income; as it is, the balance gets destroyed when I earn a lot of money.
Since a big part of my income has always been looting/sieging, the rise in cost hits harder and harder. 1200g, independent of my rank, the quality of the county/duchy in question, etc etc etc - it just makes fabricating claims a tool not to use anymore once I built a nice demesne. That's 11 or so months of income out of the window. I'm not complaining that I can't afford it. I can. I'm complaining because the fabricate claims tool has gotten worse and worse. That's not really an aspect of a good balance.
Balance doesn't mean you can keep gobbling up provinces with a low cost-low risk fabricate claims mechanism. It's a tool in expanding, not the tool. If you've grown so large that FC costs have become prohibitive, then you'll need to find other means. As you should.