Why do you think they haven't ever ported Doom 64 into a collection like this?
Seriously, I loved Doom 64 - it felt like the last true Doom game to me, and it is near-unplayable now on the Nintendo 64. I would love to be able to play it on the computer with better controls and an achievement system, but it seems like D64 is forever going to be the forgotten member of the Doom family.
I miss games like Doom 1, 2, and 64 where the levels were wonderfully designed, there was little story, and the object was to pop in, find keys and switches, and move on. This style of FPS has virtually become extinct, but it seems like there is still a market for these types of games. Isn't that why we continue to return to Doom after all these years?
I wish some developer - not even just ID - would make modern/updated versions of the awesome "unleash hell" level-based shooters again. It would be nice to have a comforting, awesomely-simple game mechanic with gorgeously modern graphics. It seems like they are becoming forgotten in lieu of games like CoD zombies and Killing Floor and other wave-based shooters.