Re: Valve should fix this.
They have a large back catalog of 32-bit titles that people still want to be able to use, and that they want to keep selling. Even if the new ones are 64-bit only (and I would think that would be the case even without this Ubuntu thing), the old ones are still relevant.
In the case of WINE, they say that most of the installers are 32-bit even if the programs themselves are 64-bit, and certainly Windows devs are only concerned with whether it works on Windows. I would like it much if developers for the Windows platform would take care to make their products at least WINE compatible if they don't wish to do a full Linux port, games and otherwise, but I'm not sure any of them ever have considered it.