Some of those mobs and bosses that you want to defeat for gear(some of which isnt all that great, imo) are capable of wiping the entire team. Depending on the gear and experience makeup of the team, skipping some of the content is not necessarily a bad idea.
Shoot holes in your own arugment a lot? How does one get experience killing a boss? You read up on it and then do it. How does one get gear? You kill the bosses that drop the gear. Skipping bosses does not help with these things. Now yes I understant the desire of skipping. Heck I have even done it myself, a lot. Running the same FP's over and over on my sin tank on it's way to 50 (my 4th 50 btw) gets old quick. But if someone says hey I want to do the bonus boss I'll do it. I'll even sit throught CS's while you speed runners are screaming "SPACEBAR!!!!!11!!!!1!!!one!!!1!!!" just because one of the DPS'ers in the group hasn't experienced the content before.