To be fair, Britain has a reputation for being rainy, so perhaps it was once considered to be a lovely thing to have a warm summer!
Nowadays, perhaps there is more awareness about skin cancer, dehydration, heat-related illnesses, global warming and so on... and the media often likes to hype things up, especially when there's little else of news-worthy interest going on in the country at the time.
Personally, I wasn't born in 1976, and not everyone likes hot weather. You do; I don't. While you have fond memories of hot weather in your childhood, I was not a fan (especially when it came to the dreaded annual Sports Day), as I have very fair, sensitive skin...to the point that parts of it do not tan at all. Instead, they turn lobster red and BURN. Despite the dark hair, I am an honorary ginger person in disguise! Thus, I have to cover up, even in hot weather.
A lot of people who work indoors have said cheerfully, "Lovely weather we're having, isn't it?" and it might be for them, as they get to sit in air-conditioned offices.
Unfortunately, due to my job, I cannot avoid being outside in hot weather. The only air-conditioning that I come across is in the newer tractors and JCB. I apply suntan lotion. I wear sunglasses because the world is too bright for my eyes. Sometimes I wear hats, and I always avoid wearing my hair with a parting in hot weather because it burns. I try to drink plenty of water, otherwise I get awful headaches, dizziness and sometimes vomiting. Hydration also helps as I have an active job. I still get incredibly itchy legs in heat, and wake up to long scars that have drawn blood from where I've scratched overnight.
Also, given the current weather, the grass isn't growing as well as it should, and our dairy cows haven't wanted to go outside, either. Staying indoors means more shade and more water troughs available to drink from! It also means less risk of heat-stroke for them. Needless to say, they haven't been very impressed to be turned outside overnight!