I consider XML to be in the same category as COLLADA. ie, designed to reliably convey data between different systems, and nothing else.
- They are both text-based and inefficient at storing data when compared to binary formats.
- They can have complex structures that lead to slow parsing especially on larger files.
- Despite what people say (and the original design intention), XML is absolutely not human readable.
The only difference I see is that people realised what COLLADA was intended for and treated it accordingly, whereas XML was (and still is) abused.
I've worked on a project where the original authors thought it would be a good idea to create an entire XML document on the fly using string concatentation, pass it to a stored procedure and query it as a table to pull out a few parameters.
Guess what brought down the entire system?... "&".
Granted, that's not XML's fault, but still...