If you set the side mirrors so the view is wide of the back corner of your vehicle, you may enjoy the convenience of a wider view, but you will also have created a brand new blind spot that can’t be remedied by a turn of the head. An overtaking motorcycle hanging off the rear corner of your vehicle will be nearly impossible to see.
And if taking your eyes off the road for a second is hazardous, that’s a situation where you’re already doing it wrong if you’re trying to change lanes
He’d have had to actually be in my lane, hanging out there, having found a way to enter the blind spot without me having intersected any of my lines of sight. That’s pretty hard unless he’s working with someone else trying to distract me. In which case mirrors aren’t my biggest problem, because they’re probably carrying a magnetic bomb.
The most important blind spot is where a car lawfully operating could be entirely invisible to you. If you’re in a fistfight, you don’t protect your nose by keeping your eye on your nose. That’s what you’re doing if you keep an eye on your rear fender. If an object is in that zone, you’ve already lost most of your opportunity to react.
Just try the test I’m proposing (try various positionings of car and mirror to see what works). I think you’ll be surprised. If not, then you’ll be able to surprise me.
As an analogy, this is entirely irrelevant. I’m not suggesting anyone looks at any part of their own car. I’m saying it’s useful to have sight of the volume of space immediately adjacent to it.
In any case, I think you’re trying to fix a problem that doesn’t exist (for me at least). My car has dual contour wing mirrors (and I think these are pretty standard now) - the view extends from the side of the car, all the way out so as to be seamless with my peripheral vision with head turned about 30 to 40 degrees.