Interesting manifesto, though I'm confused as to why you bring Doom 2 into this. Doom 2 doesn't take much for it's requirements, though some mods do and some don't, so why bring Doom 2 modding in general into the title and at the end?
Especially considering the part on "Low-poly 3D environments" which depending on the old engine used could use about as much hardware power as Doom 2.
This said however, I do think mindfulness is a good idea for people making anything and optimization is important, it's also very taxing depending on the project which is a real sap for the spirit, but it's not a bad idea to start out low and small for people getting into games. I can't claim I do that as I bounce around with various programs advanced and old, but I can appreciate the experience of starting small and grow big on making things in the realm of gaming.