>>Why is warming always believed to be bad or, in your words, a “sad” thing?<<
Because the scientific analysis so far have been pretty uniformly negative.
Negative?
Doesn't that depend on what your definition of "is" is...?
You confuse the message with the messenger.
Yes, but it is scientific analysis with a definite bias toward catastrophe and hysteria which their sponsors want to hear. If they don’t toe the party line, the funding dries up, jobs are lost, graduate students will not receive money to pursue their studies. Follow the money.
Open your eyes, read a little and you’ll find a lot of scientific analysis that is contrary to what you believe. Then, look at the historical record, ie, the MWP and the little ice age. No “scientific analysis” needed there — you can observe the impact of cold vs warm on mankind and civilization.