Valve didn't decide to pull it, and the game is still downloadable if you purchased it before.

How is this gabes fault? Should gabe ban people from removing their own games from the store?

It's unlikely Valve forced the game off the page. Even so, the supposed issue has always been if Steam were to pull games from you that are already in your library (which AFAIK they haven't) or a future hypothetical where Steam closes down and if people would be able to offline save their libraries.

It's not about the IP. It's about the actual piece of work.

Imagine if I drew a new version of the Mona Lisa, and they destroyed the original to display mine instead.

Preservation, while perhaps idealistic, is about keeping every version that we can. Doom is a great example. Because Carmac released the source code, source ports have proliferated. That means anyone can play the original Doom on just about any machine. Varying degrees of accuracy to the original DOS release exist thanks to ports like Chocolate Doom, GZDoom, Eternity Engine, et al. As do varying degrees of accuracy to Doom 95, the Windows 95 rerelease. Or to the version running on Xbox packed in with Doom 3.

Ports cover the engine, but we also have an archive of all the doom.wad files, the contents. We have demo and prototype versions. The dos release. Officially patched versions. The win95 release. The Xbox release.

But a preservationist also wants the original Bethesda Unity release, wad and engine. The Kex release with the new engine and new episodes. Neither of those Bethesda engines needs to exist but why not keep them too? They're a part of the Doom legacy, an ongoing chapter in the endless story of Doom.

Its good that in this community we've gotten to preserve so much. It keeps the history of one of the most important video games alive and relevant. It keeps the game itself relevant. Without the original source release, there's no GZDoom and there's probably no Bethesda rereleases. The impact that source release had on the gaming community, gaming as an industry, modding and indie gaming, is incalculable.

That Crysis--also a landmark game in its own time--deserves any less is laughable. The original release of the game should always be present and available: as an artifact of its time, as a fine game in its own right, and as a piece of living history that can be stood up against its remakes, sequels, and the games it inspired.

I agree with what Kolanaki said -- it should be available simply because it existed, not just because people will want to play some version of Crysis. My preference is that each patch-level version of a game should be made available somewhere for people to check out. It's not simply about a product being available that satisfies some need or desire (in this case, the desire to play Crysis). Works that people have made should be available for others to explore.

Also:

If there was no alternative, and debatably superior

is that true? I'm genuinely asking. I think I actually own the remastered version of Crysis, but I haven't actually played it, as I also have the original on Steam. I thought the remastered version was a graphically improved version of the console port of Crysis, which made some changes to the way that your powers activate. And I remember everyone disliking that when the console ports first came out.