Why do you think that 4, 6, or more cores is overkill for the average consumer? Have you ever tried to burn a DVD, surf the 'net, while Norton does a whole-drive virus scan? That combination will bring a single-core machine to it's knees. What about scanning a folder full of hi-res digital photos? Have you ever watched a single-core machine try to render row after row of thumbs? On my old single-core (Pentium 4) it would sometimes just completely freeze, to the point where I'd have to walk away from it for several minutes.
On my new i7, I have yet to see it slow down, no matter what I'm doing. And that's not "power-user" stuff - just perusing large folder of photos, while burning a DVD, and not having to worry if Norton decides it's time to scan the whole hard drive.
More cores == you, happier, trust me.