I don't understand how the west didn't see that they should at least accept to exclude Ukraine from NATO. Why, giving in to Russia's demand (even partially) would be a loss for NATO?
Probably not, in the long term, and the ability to prevent similar coercive efforts against other nations near Russia would be far less.
What would the world have got in return from Russia? A solemn promise, a ratified agreement in writing and everything, that Russia would make no demands or incursions on Ukraine's sovereignty and territorial integrity?
Yeah, something like that would be great.
Except that's what the world already got from Russia, in exchange for Ukraine giving up its nukes back in the 1990s. And look how much that piece of paper was worth.