Here's a good reason not to use untyped datasets.  I was tasked with hiding a radio button on a webform depending on the SkuType of the product.  Unfortunately I have no idea if the web application, let alone the web service it uses for data access, returns the SkuType already.  The web service just returns a bunch of untyped datasets as raw strings.  To actually figure out what each web service call is returning I have to look at each sproc's SELECT statement.

If I had some hint in the code of what the expectations of the form of data, I could at least grep for SkuType.  As it is now I may be adding it to an existing sproc, thus unknowingly duplicating logic.  I guess my only alternative is to export out all sprocs to a script and then grep the script for SkuType.