Pretty much everything in your system depends on libc, and when you try to remove a package that other other packages depend on, the package manager will most likely remove those as well. Meaning, just about every 32-bit package you had installed were removed.
Haha, wonderful! Thanks for the explanation. Still getting the packages back, I'll just leave it as is this time.
marzelut, had no clue steam gets you libraries for linux, that's great. Haven't gotten steam yet for linux, might try later then.
Steam pretty much comes with a stripped-down Ubuntu 12.04, and prefers using those libraries rather than ones supplied by the system. This can both help and hinder - running on Arch, Steam's libstdc++ and libgcc_s libraries are incompatible with my system, so for every time Steam updates (and replaces those files with its own), I have to remove and link them to the system libraries.
thing about the Steam runtime is that game developers can focus on getting their games to work in that environment and won't have to worry (as much) about being compatible with other versions or implementations of various system libraries, decreasing the work required for a Linux port considerably, and increasing the likelihood of Linux ports.