I believe we all agree about the facts, just not about what constitutes an "important change".
Most people lives were unaffected; most people kept their language, their traditions etc. For contrast, compare with: the third Punic war, setting foot on America in 1493, the industrial revolutions...
Some of us have just decided that's where we draw the line: An event that is important enough to wipe out and replace the whole ruling class but that does not change, one way or another, the way people live, is not "important".
It is true that in the immediate aftermath of Hastings, life for most folks continued on largely as it had before.
But in the longer term both the administrative structure of the country (which very much affected individual folks' lives) and the language were significantly changed.
I don't see a reason to privilege one of these over the other. You could make the case, for example, that WWII was of little consequence because Germans today live much the same sort of life that they'd have been living if there had been no WWII. That's not clearly a false claim about people's lives, but it doesn't really serve the purpose of understanding the consequences of war very well.
Most people lives were unaffected; most people kept their language, their traditions etc. For contrast, compare with: the third Punic war, setting foot on America in 1493, the industrial revolutions...
Some of us have just decided that's where we draw the line: An event that is important enough to wipe out and replace the whole ruling class but that does not change, one way or another, the way people live, is not "important".