Some dated gear's appearance no longer exists. That's really the only reason I kept mine around. However before 2.0 some dated DoH tools were actually useful while leveling. I haven't checked to see if the stats have gone away. Blacksmith for example -- I kept a full set of dated and regular tools for when I level. In 1.0 the dated were sometimes superior. We'll see in 2.0 but they probably nerfed everything.