Ranger/Warrior sustained damage dealers, in my opinion, are better than W/something sustained melee damage dealers in almost every respect. You miss out on the armor penetration of strength, and some of the good damage skills in that line, but you more than make up for that with being able to spam your energy based attack skills without having to worry about running out for a while. With a warrior primary if you want to use energy attack skills often you have to bring a skills for energy management, i.e. bonetti's defense or flourish, which is one less skill that you could be doing damage with.
Okay, thats energy, but warrior skills also come in adrenaline based versions. Tigers fury, the beast mastery skill that gives you +33% attack speed, is perfect for these. But, if you're a primary warrior, 10 energy to keep casting it every 10 seconds is too much, but if you have expertise, it'll only cost 6, letting you get those adrenal skills charged and do damage faster.
BTW, should this thread be moved to the build discussion forum?