Last I checked, we
were living in a free society run by the great laws of supply and demand
Turns out, there are a
great deal of people who game on their notebooks, you know, when they're not working 24/7...and it's a significant enough minority that Apple ought to at least offer an option for a decent GPU. While it may not be possible with the current TDP levels, it is certainly a valuable thought experiment to expect that they will do so for the next iteration(s).
And gaming on PC/laptops is hardly "dead" or relegated to merely console gaming - people have been making that claim since ~1998, and companies like Blizzard would love to disagree with that (their revenue sheets tend to help their argument too

)
Finally, it terms of pure competition, Apple
needs a solid response to the highest-end PC's such as the Sony Vaio Z (13.1" 1080p FHD, i7, discrete gfx, carbon fiber). As it stands, the MBP 13 is the ugly duckling of the

family