How do you know that?
As for TOS, is it acceptable military doctrine that the general and his staff are the ones taking point into danger, where the entire leadership layer can be easily erased? Did Eisenhower storm Omaha Beach on D-Day?
Picard was much closer to a modern naval captain: his ship had a clear chain of command and it was part of the plot that his xo did the dangerous expeditions so he could remain in command of the overall mission.
I would add that Eisenhower was a general of generals in d day. Generals closer to the action would sometimes find themselves in danger. For example Roosevelt Jr landed under fire and received the Medal of Honor. And for ship captains that was quite a bit more true.