Its only a bit of snow

[Niall]

But there not unnecessary. You forget car that our winters are changing and they are getting colder, wetter and if the past 2 years are anything to go by, snowier.
Personally I think it's a good idea and there is no extra cost because if you are using two sets of tyres, you will get double the time frame out of them as you are doing less miles per year on a set so theoretically, it shouldn't cost you any extra at all. Just means you have a slight bit more reassurance in the winter months.
And if you slid to a stop, you weren't driving to the conditions or you just can't drive.