I bought a K-1 because it was ~100€ more than a KP, and it has more buttons* and a brighter viewfinder. The only lens I had to substitute was the Tamron 17-50/2.8 so no biggie.
Regarding modern lenses and whatnot: I like my test charts printed B0 size, in screaming pink. I can pass them off as Kandinsky works
It is also disingenious to take a 3.75x zoom and compare it with prime lenses that, used, cost (for the 21/40/70 trio) about as much as a new D FA 28-105.
*I use most of the dials and buttons and I like fiddling in general