If people play, it becomes popular, which attracts more players, which attracts spending. Even if you spend $0, you are still supporting the type of game it is by playing it.
Discs have just been a physical license key for a long time now. It's kind of wasteful to even ship discs and the plastic cases anymore, some kind of little card with a chip on would suffice.
DOOM 2016 captured the essence of the originals with some added systems, but they never felt too invasive. Eternal threw that out the window, seems like this is the same. Just more AAA slop for insane prices.
It sucks but CO missed its opportunity. It's a mod that's been in development seemingly forever. The main guy was constantly making side projects with no updates on CO. Another project called CS Legacy was announced recently and then all of a sudden we hear from CSCO. Apparently CSCO submitted a build in October last year though, but still, it feels like they sat on the project until something else forced them to get a move on.