Re: Trundle - I have the same feeling about most of the sustain melees like Warwick or Irelia. If you aim to build pseudo-tanky, the natural sustain plus lifesteal should be a very big asset to a team.
I build Warwick with the intent of sticking to a target and soaking as much damage as I can. BotRK, Spirit Visage, Frozen Mallet, Runic Bulwark, and Hydra are all things I want to go for when I have innate sustain.