Mike presented very sound arguments for the differences between decades of technology and performance enhancements we are seeing today, although tires are much better performing today, the offset as mentioned is in tire size which is working against winter driving performance (speaking of non winter tires).
I'm an advocate for the use of winter tires, I used to drive for years only using all season tire during the winter and can attest to the superior performance of a winter tire over an all season tire. Yes, you can get by in the winter with all season tires, so I don’t think winter tires should be mandatory. But, as I complained in an early reply rant, why should my safety and time be compromised by those who choose to drive unprepared for winter driving (whether that be; driver skills, tires). It is a matter of respect and consideration for your fellow driver.
I hear the argument “I can get by using all season tires” all the time and in most cases it is a true statement, that driver went through winter without an accident or getting stuck somewhere. But what will it cost to minimize this risk? Not much in my eyes, yes there is a large up front cost to have a 2nd set of tires, but in the long run, there is wear tear on both sets, so there is marginal long run cost of running 2 sets of tires, isn’t that worth it for your safety and others around you?