The warrantee issue I mentioned was fraud--that is, sinking costs into investigating additional warrantee claims which turn out to be due to user manipulation. I suspect this is less of a concern compared with the legal liability of injury resulting from modification--I imagine it behooves the company to be able to point to the EULA and say, "look, we're doing everything we can to make sure this doesn't happen". This is complicated by the fact that they have to comply with laws in virtually every second and third world country, not just the US. It's just easier to be conservative with a blanket EULA. They could probably devise a more nuanced approach, but it would probably be costly and they probably have better (read: higher customer value) things they could put that money toward.

This is very similar to CPU overclocking. fraudulent warranty replacement claims were rampant untill recently but that intel fixed it .