Hever had it before, but then I've never had an electronic parking brake before.
Ironically, the loan 116i that I had had hill start assist and a normal parking brake! I wasn't aware of being able to switch it off.
I can't see how it can drive you mad....if your pointing uphill, put car in 1st, clutch down, brake pedal down, release handbrake and then hold car on footbrake. Then, release footbrake onto throttle and then mix throttle and clutch etc as normal to pull off. Hill start holds the footbrake for a few seconds after you release to stop the car rolling back.
If your clutch control is good enough you may not need it....but then, you wouldn't notice it, so I cant see the problem.
Same pointing downhill in reverse etc.
It comes down to personal use/preference but the underlying issue is the car was sold as having it...when in-fact it didn't have it. If someone buys the car believing it to be present, then has no confidence in driving it due to its absense, then it is a big issue - unless the dealer are going to underwrite and accidents caused by not having it?