Cold, damp, tired and hungry after a day of climbing, making fire is not just a means to keep warm.
Drying clothes, cooking food and keeping away predators (perhaps not in England) are all good enough reasons but when the day has ended and exhaustion sets in, there is nothing like the crackling of a strong fire on a crisp night to recharge your morale.
Sometimes starting a fire can be far from easy, but it is always worth it.