I assume the closer you get to 50 you will see more variety so maybe things will get better in due time. But as I type I am killing Maidenbugs that would only use Spoil on me time after time, Djiggas only do Mortal Mist. Looking back at the past 20 odd levels, I only see puks do backflips, moles dig, etc. So 1-2 skill moves per monster race is the norm from my observation.

For those of you who've played XI, I'd say the average mob had 3-4 skills. Sorry for making that dreaded comparison again but XI was just that good.