Let's take FPS games for example. Modern Warfare 2, the single player portion was probably 3-4 hours long if you didn't suck and didn't bother trying to get all the hidden objectives and achievements. That is not long at all, but who really bought MW2 for it's single player? Exactly, most only wanted the multiplayer/online aspect.
I'm not saying this is bad but as the internet grows more popular so too does our desire to connect and be with other people even in a virtual reality. Games such as MMORPG's are becoming more prevalent in today's gaming society. Console games are almost having to be sold with some kind of online attachment. Same with handheld games as well.
So, as it stands probably like most people I get very bored with just a games single player and just look more forward to interacting with others on the games online portion. How about you guys?