The problem isn't that this quest is hard, it is that it is so much harder than anything else that has come before it.
I'm playing an Assassin (DPS) and was at level 20 when I did this quest. Took me three tries and using some of the strategies on this thread to beat it. (The idea of kiting the mother back to the original entrance chamber is what finally worked for me.)
I can understand wanting to make the final boss for a planetary class quest line a challenge, but I think the devs went a little overboard with this one, especially for the assassin spec. Assassins are all about striking from stealth, high burst damage up front, and killing off an enemy before it can down you in your lovely light armor. This encounter was designed in such a way as to eliminate most of the assassin's advantages. Doable, but it was like going from basic arithmetic to suddenly needing to solve an algebra equation.