I don’t think I’ll ever buy a camera that doesn’t include a flash on the body itself. It isn’t that I like flash photography; I abhor it, actually. On-camera flash photography makes for uneven lighting, weird color mixes, and generally bad images. However, having a flash built into the body means that I’ll never be without a fill flash and this is very important. Any time you’re photographing something, especially people, on a bright, sunny day, pop up the little thing and let the camera work its magic. It’s worth it. 
Yes, you are right! build in flash could be very useful.Expecially like your sample photos situation, for a better photo,you just have to light up the shadow.