I can't see what the "outrage" is about. Most primary schools here do this as a matter of course. I saw this on the mail online yesterday and it was refreshing to see the comments on that article (for once - obviously not the response that the paper expected).
In the mail article, one of the parents even said something along the lines of "carpets are meant to get dirty" WTF, I won't be going round to her house anytime soon then.
Not sure though that there is any "health and safety" issue either, unless the children are involved in heavy lifting or working with heavy hand tools that would require sturdy shoes 