Live overall is very important, no doubt. Live marketplace alone makes it damn important.

Gold/Silver accounts? That's a different issue altogether. It depends on what games you like. There are some stellar single player games, so I think Gold accounts might be left unused because of this. Dead Rising, N3, comes to mind, and certainly the lag issues in games like DOA4, SF2, and the like can make online gaming pretty useless.

But I'll still support Gold, as long as I don't get bored of DOA4, which will probably happen...never