The biggest problem is that the "trusted" party which has full access is almost certainly under NSA/PRISM jurisdiction and can be forced to do things which most people would find objectionable.
What attack vector, exactly, does the TPM enable that isn't present pre-TPM?
But wait, it gets worse. At least in the case of MacBooks you only have to trust Apple, but in the case of Microsoft you also have to trust the computer manufacturer. And that's a really tough pill to swallow.
I actually hope that Windows 8 will be banned by governments in the public sector, as Trusted Computing is a scourge upon this industry.
Only Windows? HN also has Slashdot levels of ignorance concerning the legal system, patents, copyright, and the music industry, and these are only the topics I know something about. I avoid political discussions, but from what I'm told, those are just as misinformed.
Note that I am no expert in those topics either. I just took the time and effort to research those on my own rather than accept the sound bites media puts out.
When it comes to technology, there's probably no better place. (And even that I would caveat with an exception for Microsoft technologies, where you'll find more FUD than knowledge.) But basically for anything else, don't expect much from HN.
While it may not be a direct security risk per se, it represents a model of computing where the security-priorities are reversed as far as anyone not in the content-industry is concerned.
Now... If Windows 8 is any worse in this regard than Windows 7 is probably questionable, but Windows 8 has had as a default OEM-configuration to be more locked down in "secure boot" and TPM-land than it used to be.