WotC has run into the problem where because they didn't make the PH1 "builds" as distinct from each other along the lines of the 2E kits... what would have been the most obvious way to differentiate them from each other and from the Essential builds has come up short.
Very few people ever used the "Artful Dodger", "Brutal Scoundrel", "Ruthless Ruffian", "Aerialist", or "Cunning Sneak" designations to distinguish their rogues from each other... mainly because except for a single class feature, there was nothing really different from them. So what should have been a useful nomenclature at this point in time (with the advent of the Essentials names), they instead are kind of superfluous and WotC had to come up with a new term.
Had the builds been truly different and more kit-like... the Thief would have just been added to a Rogue subclass or kit list that included the Dodger, Scoundrel, Ruffian, Acrobat, and Sneak. These names would be already in our vocab, and adding the term Thief to the list would have been cake. Likewise, the clerics would have the Essentials Warpriest joining the Battler, Devotee, and Healer (or whatever better names they had come up with at the very beginning.) But since the builds were not as concrete as this... all fighters were just fighters even with slightly different powers or mechanics for certain class features... this terminology has been unused.
Unfortunately, the shift in their design to Essentials turned what used to be fairly lightweight ideas of "builds" into a much more defining aspect of the class... thus the need to make more substantial names for their older, more namby-pamby builds.