Maybe I'm just a sucker for marketing, but the whole reason for the "Optimus Technology" was that you could effectively "turn off" the power hungry nVidia graphics when you weren't playing games. Yes, that means Intel is selling integrated graphics, but that silicon is useful for power savings. It doesn't seem like a bad thing.
No, you are absolutely correct in pointing this distinction out. There is indeed a place in the market for this dual GPU setup. The Intel GPU provides for much better battery performance over the discrete graphics card and switching between the two can be very useful.
A simple metaphor would be like - why not make a Ford F350 get 35 mpg instead of owning a Fusion Hybrid for commuting during the week?
Limits of physics and engineering.
Will a reasonably powerful gaming card eventually draw the equivalent power of an integrated chip (when not gaming)? Probably. It seems like we're not there yet.
