I dont know where you live so you may not get a lot of snow, but for a lot of places, just knowing how to drive isnt always enough. Sure, getting 10-15cm of snow and slush isnt too bad and if your careful can be no problem, but when your getting 30+cm in a 10 hr span, or freezing rain so bad you can literally skate down the road, winter tires are highly needed. Not just to keep you on the road, but to keep moving aswell and not just start to spin your tires.