They are probably not necessary in your circumstances, in the same way that having a 330d over a 320d isn't really necessary, but your car will perform a whole lot better in cold weather, not just snow.
When you consider that you are only wearing one set of tyres at a time, and smaller wheels are very cheap, the additional cost of switching between winter and summer tyres is tiny.
I have been switching between summer and winter wheels for about a decade now and I wouldn't go back. Having said that, I do drive in places where I would have to choose an alternative route without winter tyres.
I also carry a tow rope in the distant hope of discovering a stuck 4x4 one day and pulling him out. Will he even live down the shame of being towed out by a BMW saloon
