For me personally, TPM is the concern because of how integrated DRM is with it. Light DRM is fine, and prevents casual rights abuse by casual players. Stricter DRM gets used to lock things up and it becomes pervasive and hard to discourage. It chews extra resources, requires more power, and eventually means that some things that probably should be copied freely eventually cannot ever really be. Just imagine if Doom had been written with TPM in mind. You would never see it running on any of the myriad devices that people have had it running on, and the knowledge gained during those builds would not have come into existence.