Well being flight deck crew, and managing an EP program, i can say that pilots are NOT always the best judge of exits to be used. Like everyone in the puzzle, they have some information but not all of it. The final assessment of exit availability is the check outside from the viewing window. The problem with fuel spills (as an example) is knowing how that spill may migrate along the ground. So even though there is risk in opening an exit if there is a fuel spill not identifiable by CC, there is also a risk in not opening a perfectly serviceable door prior to any fuel spill igniting, if it should. Its a fine line. Of course if you have an Aviation Rescue Fire Fighting service at the field, it is usually better to give them a chance to contain external fires and fuel spills before considering an evacuation. So long as the airframe is intact you have up to 5 minutes before burn through of the fuselage and insulating material occurs. That is well beyond the minimum response times for the ARFF (assuming it is a clear day/night and you are on a runway or taxiway).
How many of you have procedures for CC shutting down the aircraft engines prior to initiating an evacuation if the FC are incapacitated?