"I don't own any Microsoft development tools myself."

There's your problem ;-)

I think you can redistribute - but like you I came up short when trying to
find explicit legal permission for them to be included with non Microsoft
developed projects.  The fact that they are called "Redistributable Files" is
IMHO you sign that you can.

As a practical matter I doubt Microsoft cares if you redistribute their
Redistributable files ;-)  If they did, they would call them
"non-distributable files".  In researching the answer to your question, I've
discovered that you aren't the first one to ask this question.

In this case, I wouldn't spend much time trying to get a legal answer.  Make
sure you aren't blatantly violating Microsoft's IP and you'll be fine.  

If you want to CYA, email Microsoft Legal.