[acdha]

The reason why many developers hate XML namespaces isn't the concept but the implementations which force you to repeat yourself everywhere. I think a significant amount of the grumbling would go away if XPath parsers were smart enough to assume that //tag was the same as //default-and-only-namespace:tag, or at least allowed you to use //name:tag instead of //{URI}tag because then you could write against the document as it exists rather than mentally having to translate names everywhere.

Yes, you can write code to add default namespaces when the document author didn't include them and pass in namespace maps everywhere but that's a lot of tedious boilerplate which requires regular updating as URLs change. Over time, people sour on that.

It really makes me wonder what it'd be like now if anyone had made an effort to invest in making the common XML tools more usable and other maintenance so e.g. you could actually rely on using XPath 2+.