It's not though, is it? Whether it was raining yesterday has no bearing on whether I'd want the wipers on today, so I don't want my wipers to remember whether they were on or off the next time I use the car. The exception is mid journey, but that's fine as mine allows for that - if I get out for a coffee and get back in they are still 'on'. If I get back in tommorrow they won't smear crap all over my windscreen because something dripped on the screen just because it was raining last week when I last drove the car.
I see people complain all the time about having to switch on auto wipers but honestly, I can't understand the problem. I've driven cars with both ways of doing it and clicking 'Auto' when it starts to rain is far less annoying, IMO.
Unfortunately I've lost the argument as the last new BMW I drove had the always on functionality now instead of the helpful button. I only realised when the guy in front washed his screen and then my wipers automatically smeared all the dead bugs everywhere. Thanks