Back on TOS it was clear cut.
Kirk, Spock, McCoy, Scotty, Uhura, Sulu, and Chekov could all safely beam down together, because if there was any actual danger, they were conveniently accompanied by a contingent of redshirts who could stand in front of them.
No seriously, the OP is absolutely right. Sending the first officer plus command staff is just as bad as sending the captain.
For realism's sake, they should have had separate away team specialists all the way, something like "science marines," with the only bridge officer among them being the away team commander. But that would have entailed a radical change in the show's format and a highly ensemble cast.