I've had a set of winter wheels for years. It doesn't have to be snowy/icy for them to be of benefit, they provide far better grip when cold than all weather/summer tyres.
Reason I had to put mine on was because one of my normal tyres was down to the threads!
Waste of money? No way, £100 for a full set of steels and top quality M+S tyres, that outgrip my normal tyres by a significant margin - it was a bloody sensible purchase.