I'm not sure your theory stands up, they did all those comics around TF2. They hired those old man Murray dudes I thought just to work on narrative. They've gotten famous actors to do roles!
I think saying halflife was never about story is just wrong.
If you stripped dialog from portal you'd have a significantly worse game. Did you forget all the glados shit that came out after portal? Humor is a major part of those games which is all about dialog.