For example, I really enjoy the solutions that Valve/Steam and Blizzard/Battle.net came up with. I give them a CD Key and they give me unlimited opportunity to download and install the game that key goes to. Steam even goes one step further and ensures that it's updated.

More importantly, neither of them require online interaction - you can set Steam to an "Offline Mode" in case I want to go an airplane or my Internet connection isn't doing so well. On top of that, I regularly max out my downloading speed when moving games around on Steam. In Steam's case it's much more convenient than pirating (don't have to check for quality, no cracks to apply) and adds even more value (checks for updates automatically) to the game. On the flipside, it's exceptionally difficult to bundle up games shared from Steam - but the gifting codes are just as easy as buying the original game. Blizzard hasn't yet made it too difficult to bundle, share, and upload a downloaded game (other than multiplayer not working due to CD-Key issues), but I find a lot of my value in the multiplayer component.

That kind of direction, where DRM adds value to the game rather than adding layers of complexity, is the direction I wish DRM would go in.

The functionality you praise is not a function of DRM, though. You could easily provide the opportunity to download and install the game multiple times without DRM.

It will become an issue once steam goes away.

As an example how copy protection can bite you years later: I have some old DOS games that verify the CD-ROM. Not if you try to run them in DOS-Box or something, you will have to find a DOS driver for your CD-ROM drive (at least I had the issue once, when I still had an SCSI drive. Not sure what it would be like now). Needless to say, I haven't played those games again. One of them was "Little Big Adventure" - it is a shame that such gems will eventually be lost forever.