The DVD screensaver was perfect: unobtrusive and did what it was supposed to do: prevent your CRT screen from burning-in an image. On top of that, it gave you something to look forward to when it would perfectly hit a corner (which some people thought was a myth; sadly the GIF version does not).
Now, any screen in your home is fair game for intrusive ads. Why make something simple, elegant, functional, and unobtrusive when that otherwise idle (or even in-use!) screen can be crammed with ads.
The dvd screensaver was just another screensaver at the time. There used to be cool things. Like install windows 95 or 98 and there’s default screensavers that were basically just programmers showing off - the pipes constantly growing into each other, a starfield, a generative maze that you just wander through, etc. then there was a whole thing for people to make screensavers (Uniqlo made one of the coolest ones).
Now computers are stupid and monitors just turn off. To be fair this is probably better for the environment
Programming screensavers is just fun.