In winter conditions the main reason why to have winter tires is always safety. It is not safe to drive with tires that are not designed or approved for winter conditions. You have the option of choosing studded or non-studded tires, where the studded will give you a bit more control, especially on ice.
Since winter tires are designed specifically for winter, they have a flexible rubber compound with a precise tread pattern that are designed to channel snow and slush and grip on ice.
With no compromises made for different seasons, drivers will gain from notably multiplied traction in the course of acceleration, drastically shorter braking distances, and ability to maneuver and reduce the speed.
Not just for snow and ice: All-season tires do not perform as well as dedicated winter tires during harsh winter conditions. Summer tires do not belong on winter roads at all. When the temperature drops, the rubber compound used in these tires will get to hard to create the necessary traction. In cold weather, even on dry roads, the softer flexible rubber used in winter tires gives the critical traction needed during the cold weather.
So it is not only for snow and ice, you will need the performance during the winter season cold weather.
Longer tire life: Changing the tires due to the changing seasons ensures that your tires will last longer due to lower wear caused by having two sets of tires. Most people favor to mount their winter tires on metallic wheels and leave the alloy wheels for the warmer seasons away from the salt and sand that is experienced during the winter. This will make your wheels last longer together with your tires.
Reduced braking distance: During winter conditions, winter tires will drastically reduce your braking distance, especially on snow or ice. This has major safety implications and should not be ignored.