Actually I have seen it work over the beast lord in my fellowship and the mage couldn't toss in her pet right away due to the insane amount of aggro generation. Considering how much burn DPS comes from pets for either of those. I am not to worried that it "hinders" them and cripples them. Other classes have key abilities denied or marginalized, its not just a pet class thing. However that doesn't make the content impossible. If thats what it takes for them to give us content that takes us out of our comfort zone and challenges us, So be it.