Word to describe something that focusses so ostentatiously on its purpose that it fails to achieve its goal
I think you're looking for a term like affected.
affected |əˈfektid|
adjective
2 artificial, pretentious, and designed to impress: the gesture appeared both affected and stagy. [NOAD]
Too artful or contrived. Too clever by half(BrE). Up its own arse(BrE, vulg.)