I'll be the one to speak up. We have been here two and a half years and we drive (when I say we, I mean my husband), and neither of us has a UK license.
Yes, we know it's illegal. Yes, we know it's not good. Yes, we know our insurance coverage would be invalid if we were in an accident. And so on.
Obviously I don't think it's ideal but it's just not worth it right now for us to go through the arduous process of getting lessons, scheduling the test, and so on when we only drive maybe once or twice a year at present. We're not planning on getting a car, so the cost outweighs the benefits right now. And we are willing to take on the associated risk of negative events if we do want to drive once in a while.
DH will be getting his license (likely in a few months if possible) but it's just not something we stress about. He is getting it because we are planning an extended road trip in Europe and if we plan on driving much more than that, we think it's best to be legal for many of the reasons stated here (although I will say it's not just because laws are laws and we should follow them blindly).