Given there was a quick and dirty Obama purge of the military traditionalist generals, how large a pool do you think Trump had to even select his generals?
The clock was ticking and Trump had to make selections best he could within the universe from which he had to choose.
By now, Trump may have better ideas if these picks give him trouble. By now, he has connections to better generals, perhaps.
But none of this is an excuse for Sessions to work on second tier domestic challenges and totally IGNORE a silent coup in progress.
He didn’t have to hire any generals if there weren’t good and loyal ones, loyal to his agenda, available. He has put three of them in what would regularly be seen as civilian-type positions.