Like most others I've never really bought a system literally for a single game. Too be honest, I usually decide to buy a system long before I actually purchase it based on multiple games released, as soon as I save enough money I'll buy it even if there's no "system seller" to go with it. For example, the first few games I bought for my PS3 were Burnout Paradise, Ratchet & Clank, and Warhawk; just a combination of games I wanted on the system.
Sure, in the back of my mind I was thinking Metal Gear Solid 4, Final Fantasy XIII, God of War 3, Grand Theft Auto 4, etc... knowing that the system would have all of those to eventually. It wasn't like I was demoing some system seller and thought "OMG, I got to have this system now to play this game!"
I guess... if I waited long enough I would of eventually bought each of my systems with a single game in mind. Would of definitely bought my PS3 when MGS4 released if I hadn't already had it, would of bought my N64 when OoT released if I hadn't already bought it to play WaveRace, Goldeneye, and Star Wars, probably would of bought my Gamecube when Wind Waker released if I hadn't already bought it to play Smash Bros and Pikmin. Dreamcast is probably the closest I was to doing this but I was thinking of both Soul Calibur and Sonic Adventure when I purchased that.
I almost bought a Wii for Smash Bros Brawl but it ended up being such a big disappointment after being such a huge Melee player that I decided to pass on the system all-together.