I dunno ... i would honestly like to see necromancer with small group of skeletons, or zombies ...
On the other hand cant see much difference between 2 skeletons wich deals 1d10 dmg each and have 20 hp ... and one skepeton wich deal 2d10 and have 40 hp ...
Note that i say much ... i didnt say none.
On the other hand, there is chance for this rule to be avoided by Necromancer spells related to undead minions. :-/
I gues it was implemented for ballancing Beast Masters, or Warlocks and Wizards with familiars ...