I'm sure there's always going to be believers and non-believers of winter tires. I for one, am a firm believer and it's based on my own personal experiences. There were a few occasions where having winter tires saved my ass and I know for certain that if instead I had all-seasons, my ass would have been stuck calling for a tow truck.
One occasion was after work when we just got dumped on by snow. Me, along with a few other co-workers park in the same outdoor parking. Everyone else had all-seasons and could not get out their parking space with a couple of other people pushing their car out. We're talking about rocking the car back and forth in its space. Push from the rear, then the front, rinse and repeat. Each car took at least 10 mins to get out. There were about 4 cars, I was the last one. Everybody was ready to help push my car out but I told to them to stay back a bit. Gave the car some gas and although the winter tires spun a bit, I got my car out on its own. If I had all seasons instead and there was no one around to push me out, I would have had to call a tow. Another time was on a hill. Our area was just hit with some freezing rain. The car in front of me, another guy from work with all seaons, proceeded after the stop light and about a couple metres up, his tires started to spin heavily. The car started to 'snake' and I could slowly see it start to slide back down towards my front end. Luckily, I was able to accelerate and past him and up the hill safely to avoid what would have been a certain collision and major headache. That was the first year I used winter tires and after those experiences I will never go back to using all seasons in the winter.
I'm a very experienced and careful driver and still am even with winter treads. Heck, you can be the best driver in the world but there are times when you will reach the limit of an all season tire in hard winter conditions. Driving carefully and defensively should always be rule of thumb anytime you drive, not just in winter. There are times though when your skills and experience won't matter anymore or won't come into play, like the time people were stuck in the the parking lot. You can try to bend your luck but you won't be able to bend physics. The problem is that even though you may be able to control your own driving, you can't control what goes on around you and there might be a time when an idiot puts you in a critical/emergency situation. I once had to do an emergency stop in the winter on the highway because this lady tried to change lanes too fast in slippery conditions and did a 180 spin in front of me over onto my lane. Slamming on the brakes, I literally stopped within less than a metre of her car. I believe there was no way I would have stopped in time if I didn't have winter tires.