it will be dangerous for passengers to be walking around when an aircraft is on fire.
Yes, I'll buy that, having been the person responsible for an annual CAP 148 airfield crash exercise at night, with 110 Casualty Union people and a full turn-out of all the services including the ladies serving tea, which was marred by a Local Authority fire tender running over the legs of a CU person feigning unconsciousness as briefed in the hope that some one would find him, 100m from the scene. The Risk Analysis didn't think of that one, which took a bit of explaining..
But
severe injuries in the process of leaving the aircraft, apart from burns, are not common at all.
PS I just watched that China airline fire video. Long way from the Fire Station, was it? I'm sure that PPRuNe has been through all that, just a comment. Good evacuation, though. Makes you realise why overwing exit seats give a false sense of security; most fires involve engines/wings and the centre/wing fuel tanks, so that from the overwing seats you're in the back of the queue for the usable exits.