[adsims2001]

"A lot of the complexities in these file formats reflect features that are old, complicated, unloved, and rarely used. They’re still in the file format for backwards compatibility, and because it doesn’t cost anything for Microsoft to leave the code around."

That's not really true. It is not free to leave old code around.

[jlarocco]

It's not free, but taking the code out isn't free either, and keeping it around makes it easier to sell upgrades to newer versions.

[acbabis]

I agree. A more accurate explanation is that it would cost Microsoft money and/or reputation to take a feature away from people who take it for granted. As the de facto enterprise solution, they're stuck supporting their old mistakes.