I do not understand why people feel the need to generalize about any group.

Making generalisations about groups of people and things is and always has been a normal part of how we deal with each other. Sometimes it's done as a way of structuring the world, sometimes it's done in fun, as a kind of game Sometime it's done in hate and contempt, and when that happens it needs to be sat on hard. But that's no reason to rule it out in other cases.

"I love folk music" is an example of a valid and useful generalisation. But of course it doesn't mean that there aren't some types of music that can reasonably be described as folk music about which I am less than enthusiastic. "Mudcatters are a good bunch" - but some of them (very few) are not too nice at all.

I continue to be bewildered why anyone should have got aerated about a thread such as "Why are Americans fat?", but a lot if people did. Would a thread asking "Why are Americans so sensitive?" be equally likely to draw fire? I won't risk it.