One of my biggest pet peeves is when sites don't use label tags, especially around radio buttons. How much does this bother me? I actually emailed my bank's support email address about adding label tags to their "Make a Payment" page. So far, nothing has changed.
Why force a user to click the small circle when they could click the text instead? It's such a quick and simple thing to do and yet can make a page so much easier to use. There's really no reason to not use label tags other than developer laziness.