If I'm going to spend a cent on a Steam game, I need definitive and absolute clarification on the following scenario: I buy the game off Steam. Time goes on, and it eventually gets uninstalled, caught in a hard drive crash, left in the old HD after I make a new system, etc. Ten years from now, I have a nostalgia kick and I want to reinstall and play the game I bought on Steam*. However, Steam is now dead. Do I now have to track down a physical copy off eBay, even though I already paid the money for an online copy? What assurance do I have that I'll always have the game available to me for as long as I wish if I purchase it on Steam? That possibility alone would drive me to just go to the store and buy a physical copy of the game, or order one from a gaming store (which, just to remind some people, has always been an option if you're too lazy/busy/fat to saunter down to Gamestop and purchase a copy).
*Yes, it is very likely that this could happen. I often play games years after they leave the market. Just this week, I started playing AH-64D Longbow again (and unloaded $50 on eBay for a sealed copy of Longbow 2. Merry Christmas to me). I also keep my disks for OMF2097, Tyrian, Incredible Machine, Sierra's Lode Runner, Space Quest (released in the late 80s), Monkey Island, Rocket Jockey and Death Rally handy, and they all get some playing time every year.