Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.
I think Pentax has made some excellent choices with this camera. Most importantly, the simplified control layout will have a lot of appeal for beginners looking to upgrade from a smartphone to a DSLR. You only have to read some of the beginners' questions on this forum to realise how bewildering all the buttons and dials on a DSLR can be for people just starting out. A non-scary looking DSLR is a great idea.
As for the optical vs electronic viewfinder: switching to an EVF would be the beginning of the end for the K Mount. It would be pointless making cameras with over 4cm of empty space where the mirror box used to be, just to keep the correct lens registration distance. An EVF would have to mean a new mount with a shorter flange length, plus an expensive new range of lenses, which is a heck of an investment in a crowded mirrorless market. With the K-S1 they've made the very sensible choice of keeping an optical viewfinder, which saves development costs and also offers a marketing lever: a mirrorless-sized camera with a full optical viewfinder.
Remember that the big hump on top of the camera isn't the pentaprism's fault anyway; the prism on an APS-C camera is actually tiny. The reason for the hump is the built-in flash that the market demands.
And if I hear one more complaint about the freakin' lights I'm going to smash my keyboard over my head. Does anyone really think Pentax would be dumb enough not to include a menu option to turn the lights off? The row of lights on the grip are just the self-timer countdown anyway--just an updated version of the red LED that already flashes on your existing DSLR.