There's normally the "Order" dropdown in the area

True, but not in the "feed" view.

longer term solution of introducing a "filters" bar or "options"

That's a good idea. I would also favour that. But these would have to be quickly accessible. Clicking through to the profile settings would be too much.

I've got a feeling I've removed that style in a previous release.

Oh, that's right too! After your hint I saw that the line came back in one of my later merges... don't ask me how that happened. So the fault lies with me :-D