I have no problem atm 2 vampiers, 1 Bat and a Werewolve ... but for a later Dark mage some kind of assassin, or something. A pentagram (Warlock) can summon Human Rogues out of a Pentagram, looks a bit strange ....
You have your opinion, I have mine, but to write I should summon only demons if it bother me? Sure I could, I can also write my own rule if I want that.
This is not the point.