Blizzard said:
Yes, and I remembered the comment when I was reading it.
However, like with every piece of advice in this thread, someone else says the opposite, and I seem to recall someone posting a couple of weeks ago saying that no matter what, bloodrazor will always do less damage than more AD/crit/AS/whatever, because the %HP magic damage bloodrazor does can be reduced by magic resistance. Something like that. And it's not like warwick will ever have AP or magic penetration.
I didn't see your Annie, but I'm going to guess they were either A) new or B) trying to use a mejai's and failing miserably or C) both.
Magewick is pretty common actually. It's extremely viable in lane. Start with a Doran's Ring or Faerie Charm (then build that into Philo) for the mana regen, take magic pen marks, grab magic pen boots, spirit visage for the extra heal, then Wit's End, Malady, and Madred's. There was a point where Lanewick was brokenly OP both top and mid.
Edit: As for Trundle. I'm pretty good at him, but he's extremely fragile as jungle, so make sure you are following some sort of guide to a t. His ganks are pretty great though.
I find he's pretty unstoppable late game if you get to that point, he has natural CC reduction, and ult that does damage and makes him super tanky, a natural AD buff, and pillar of filth is freaking great ability. Build him a lot like other junglers: Wriggle's, Merc Treds, Spirit Visage/Trinity Force, Banshee's/other Armor item, Guardian Angel.