I almost never use pop-up flash for light in a dark scene, but I do use it for fill, especially when on holiday. That's exactly the situation where I wouldn't consider a hot-shoe unit because it adds space.
I imagine that Pentax/Ricoh had this change in mind when they announced the AF201FG mini flash a few months back (
PENTAX - AF201FG). I also imagine that there will be some kits available with this flash bundled and that may go some way to mitigating the removal of the inbuilt unit.
It's important to remember
why the flash was removed - it wasn't to make the camera smaller or to allow anything important to be added - it was to add GPS, something that is undoubtedly far, far less important to photography than a flash, even a pop-up one. That's what makes it a bad decision.