Hardware vendors that manage to do that, will certainly have a superior offering in that regard.
I think you are hinting at something useful: there should hardware requirements and then Qubes-relevant hardware features,that go beyond the certification.
Examples of these (some as you point out) could be:
- webcam/mic killswitch
- upgradable RAM
- allow for multiple sys-usb (2+ usb controlers)
A feature breakdown like this would enable a more robust product comparison. And this is something that we can already get started here on the forum. All one needs is the initiative.
My suggestion would be to add to the community-recommended computers a table with these “beyond-requirements” features. That is a wiki post, which means anyone can and is welcome to edit. All certified hardware should already be there, so I think it would alleviate your concern. Would you be interested in shepherding this?