It is easy enough for a spell caster to control undead lots of ways. Then they could cast this spell for every ability and feat they have to enhance the undead. And every time they get a couple levels and a new feat, they can just cast the spell again.
And you can only make a limited number of types of undead, so you can only apply your undead creation abilities to them. But with this spell, you can give them abilities to any undead. It just looks like too much.