I have the 24mm STM pancake for my 70D. In fact it is my default body cap if nothing else is mounted. It is a relatively compact package and I've taken the combo out a number of times, but I agree it is no compact camera.
Frankly I find the Canon M (original) + 22mm f/2 pancake combo to be much, much better for the ultimate in compact kit. An added benefit is the f/2 vs f/2.8 which leads to better bokeh (when desired) and better night time, low light shooting (bars, restaurants, night life in Manhattan, etc.).
So in short, if you are looking for a light/compact kit, the 70D + 24mm pancake just doesn't go far enough IMO. The M is about as good as it gets for small size while still getting an APS-C size sensor.