Alexander,

I think you may have answered your own question.  If Matt Cutts says they are fine but don't use them to increase your potential keyword percentage, I wouldn't do it.  If you utilize a tag cloud to help navigate your site/posts/pages then go for it.

As always, it always comes down to quality, unique content.  There is no way of getting around it, so just build excellent site navigation, and proper linkage in your homepage content and you're set.

Best of luck.

If I am understanding Rand and Todd's opinions correctly regarding this subject:

Rand believes it doesn't matter.

Todd believes it does matter and can be beneficial.

To me that would say to err on the side of caution and choose Todd.  Not because he is correct, but because there is no harm in doing so either way according to Rand.