No it isn't, because fel mastery affects our single-target damage as well, which we were by no means the best at... all the other nerfs I don't mind (seriously, a talent doing #1 damage is just bonkers, especially when the other two choices in the row don't do nearly as much...), but Blizzard should only have nerfed AoE damage.
While it pleases me to see a fellow shooter of lightning, saying that DH's don't have to try to pull good numbers isn't very fair... I use seven buttons reguarly (with a cooldown shorter than one minute) when playing havoc and I have to make sure I press the right buttons just before and during the momentum window I tried a lot of classes before deciding on a main and I found almost all of them too shallow, so it would make me sad if the interesting spec did poop damage