Interesting. At first I thought don't fix it if it is not broken. Who has problems with bike stability anyway. They make it for the elderly. Are elderly people crashing often on bikes?
I once saw 15-20 year girl going down a long hill and the riding looked weired and extremely unskilled. Add a tiny curve and slightly uneven ground I saw her crash. I would not have thought it was possible. People on bf are not connected to this crowd. Some people need the 2 extra small wheels.
What about imroved stability trough frame geometry? Stability when stopped? Maybe tricycles but that would possible be an unbelievable image issue for people. I'm not really sure it is worth it. Derailleurs , cables and electric bikes are not really simple anymore but that takes it to another level. It is a philosophical problem with added complexity and bicycles for me.