If you're not removing the DRM on them (code signing) then what do I care?
DRM prevents you from redistributing original media (with varying degrees of effectiveness) and doesn't do much for cryptographic attestation (nominally).
These are two very different systems for different purposes.
As far as I know you can run unsigned code pretty easily still (especially, though not uniquely, as a technical user), and the process of stripping attestation/signing information from an executable on most popular platforms is well-documented with freely-available tools in most cases.
I'm almost certain there are ways to disable code signature checking completely on the major OSes if you really want to, but why you'd want to do that, I don't get.
Is your argument that running code with an invalid signature should happen with no notice, no hurdles, no nothing, by default?
Then there is secure boot which requires MSFT permission to use an OS, cell phones on which you cannot run your own code without manufacturer permission.
I hope you don't still think the R in DRM stands for rights.