It's obviously a personal choice, but there are counter arguments to both the cost and mild winter arguments.
The cost of winter tyres is mostly a cashflow issue... remember that premium summers (the Goodyear Assys and Conti 3s etc) also cost a lot, and you'll be saving wear on those while you have your winters on. You'll also save on wear on winters while you have your summers on. In effect, you're just buying replacement tyres - but all four at once and earlier than you would otherwise. Over time, the costs should even out, except for the cost of the spare wheels. But if you have a car with normal-ish sized brakes (anything in the range below the
Cupra I believe), 16" steelies are fine and available at reasonable cost.
As for the "it doesn't snow enough" point, winter tyres aren't just for snow. They are much grippier at
lower temperatures (under 7°C) than summer tyres - even more so vs premium summer tyres which have a high natural rubber content, and so tend to harden as temperatures approach zero, losing most of their traction. The colder it gets, the bigger the advantage you get from winter rubber. If you commute early in the morning and late in the evening, as many people do, you'll often be driving in temps under 7°C and winter tyres are much grippier in the chilly, wet conditions that are typical of British winter weather. The fact that you can drive and manoevre in snow (if we get any) more safely is a big bonus but not the main reason to get them IMHO.
I was sceptical too before I tried them, but I live in a little village in the middle of nowhere, with hilly country roads in every direction. Having nearly not made it home a couple of times two years ago, with my baby daughter in the car with me, I decided to bite the bullet and give them a go. I was amazed by the difference that just a tyre could make that I'm a bit of a winter tyre evangelist now - I'm sure you'd never look back if you tried them.
My missus was convinced too, having driven my car, and she pestered her fleet manager until they paid for winter tyres for her own (company) car. It made sense for her company financially, as she drives a lot for work and can't visit sites to do deals for them if she's stuck at home.
The extra insurance premium issue is absolute madness and I do sympathise on that point. Personally, I would be looking to change insurers if they tried to increase my premium just for using winter tyres. In my view, it's fair for them to want to know that you're changing wheels (if you do) and make a note that you're changing from the OE wheels, but charging you for the privilege is an absolute joke!