Benefits of the docx over the good old doc

What was wrong with the old Microsoft office doc files (prior Microsoft 2007)? This was a random thought I had, so I went out to search for an answer (I sometimes have too much times on my hands)

Here is a quick summary of my findings:

• Improved damage recovery so if a single segment or component of the file is corrupt, the rest of the document can be read.
• Smaller files: files are automatically compressed to smaller files. 
• Easy detection of files that contain macros. This can be like a preview functionality or a security measure. 

So, looks like Microsoft didn't do it just to annoy people.