It definitely isn't in the budget for everyone to have a second set of tires, just for the winter. So A/W tires are a good option, and definitely a step up from all season (jack of all trades, master of none) tires.
That is false economy. Two sets will last much longer, summers/all-seasons should have better MPG then CC2 and be much cheaper.
All-weathers have definitely taken a leap forward in performance, but I don't think they will ever truly catch up to dedicated hot/cold setups if you choose carefully with mid/budget in mind.
The start cost is a set of 4 used rims.
The issue is mostly practical with storage and hassle of actually changing wheels.