Restrictions is what makes the game interesting
Actually, it will make quite a difference because at the moment Death is virtually defenseless against creatures.
If someone attacks me with, say, a Pharaoh and starts spawning Scarabs, my Plague or Retrovirus takes too long to take that Pharaoh down. A couple of Lightnings does this job perfectly.
Now imagine that I have a couple of skeletons and command them to kill that dangerous creature. 2 turns -- problem solved!
Also, the upgraded version will be useful if opponent has his own skeletons. Turning them against him is a double benefit: they stop harming you and begin harmong him. Doing that with powerful creatures, such as dragons, would be way overpowered.