Morning excrab.
I don't think I have missed the point. You are very right when you say they should be recognisable to the passengers and, god forbid, the emergency services.
However, would a cabin crew member be less restricted acting in an emergency wearing denims and a t shirt rather than a tight skirt and heels? To use a loose analogy, you would not expect a serviceman to go into action wearing ceremonial dress.
If I remember rightly when flying with Lauda Air some years ago the cabin crew wore jeans/t shirts/baseball caps and looked a lot more comfortable doing so.
WAWKRK, a smart uniform does command respect but is it really functional when some lo-co carriers have cabin crew doing 4+ sectors a day?