The matter of winter tires really depends on where you're going, not where you live. If you're always in the Milan area and hardly ever head toward the Alps or hills when it gets cold, then yeah, it doesn't make much sense to spend 400-500 euros on something you won't use. The problem is that a lot of people think "well, it never snows in Milan" and then find themselves driving on summer tires on an icy road the moment they leave the province - and that's when summer tires are actually dangerous.
What few people consider is that the legal deadline is the end of May, but technically you should already have them on by October if you want peace of mind. Some people get around it by saying "well, I'll just put them on when the weather gets bad," but that's not a risk worth taking. If you know for certain you won't be driving in winter, then summer tires are fine; but if you ever head to the mountains, visit friends in colder areas, or simply don't know what the winter will be like, the cost is worth it for the safety rather than the convenience.
Besides, if you're not using the tires, they last longer - if you change them every year that's money down the drain, but if you put them away for the season they easily last a few years. It makes sense to buy them once and have them put on and taken off seasonally rather than trying to dodge risks every winter.