Unless you are a body builder, they are kind of a waste of time. Most back exercise you do is going to work your biceps. And the people doing them the most are probably the people that need to be doing them the least. Also its not just people doing curls, its like its an entire day for them. They're doing 3 or 4 variations of curls and doing 3-5 sets of each.
Ah, I see. I will be honest, I honestly don't care how "strong" I am, as long as I get to a body that I like to look at for myself. I care more about general health, and then getting a body that I'm not embarrassed by when I go to the beach.
My routine, and excuse my terminology as I'm a total noob, is pretty much full body workout every day, then cardio to end the night. I'll do something like: bicep curls, side lifts with free weights (not sure what these are called), pull ups, flys, backwards flys, rows, leg press, ab crunch, pull down, chest press, leg curls. 3 sets of each, at a weight that I can do around 5-10 before having to stop because I can't lift heavier.
I'm 5'7", 162.3 as of this morning. I have a small build though, and am trying to get the tone throughout my upper body (and obviously legs that fit the toned body size). I still have "man boobs" and a gut though that I'm working on. Started around 175 pounds at my heaviest a couple months ago.