As is JavaFan, I'm coming up blank on any actual utility in any current browser for the DTD; the DTD's chief value, as far as I can see, is that it's presence in the correct place and format keeps some .html validators from spitting "errors."

But if you're supporting browsers for those with restricted vision or other physical limitations, you might want to enquire of their user and user-support communities (where such exist) about any use of the DTD.

Alternately, if you're still supporting Netscape 2.0 or IE 3 or something similar, there may be some merit in using the DTD (but not much value, IMO, in continuing the support). :-)