Who says that drag and drop, or context menus, need to fail? And why would any sane user, who's spent the last 15 years getting used to the way desktop software works, want to switch to a completely different, entirely text based user interface?

Any existing user of Office will feel far more comfortable in 280 Slides than in Google's presentation app. Desktop-class applications are not always the right answer, but to say they are never the right answer seems pretty silly.