most PCs already ship with IGPs, this is the same thing, right?
Joe Consumer doesn't know what the hell a graphics card is, or really any other component for that matter. Integrated Graphics is getting better, but 10 x 0 is still 0. All the new architectures coming out are including Graphics on them, so it's obvious that this would take off, given the huge number of PCs that don't ship with dedicated graphics anyway. The average person will pay more for a "better" CPU, even if they don't know what that means, but to them, the concept of a graphics card is too confusing to understand.
The fact that the new 13" Macbook Pro is integrated only can only help this trend, because I'm sure that model will get the most sales, it's the first choice of every person I know going into college, as well as being more than adequate for most consumers.