"Without an XML Schema, you might as well replace all those < and > signs with quotes and commas, 'cuz that's what you've got - just less-than/greater-than-delimited text."

I'll be presenting this rant and many other as a PADNUG Web Services SIG meeting sometime this year in a presentation loosely titled: "Mailing a Boot: Exactly how NOT to use XML and Web Services"

Certainly schema isn't required, but when you spend the date passing DateTimes and decimals around in XML, you get used to clients of your XML using the associated schema for simple data typing.