The fact is that Binders don't have the flexibility to make up for their lack of power, or the power to make up for their lack of flexibility.
As a class their core shtick is that between picking a vestige and assigning their Pact Augmentation they can essential rewrite their class features as needed, going from archer to front line warrior to fire-breathing crowd control. In theory. In practice it doesn't work nearly that cleanly.
When it comes to flexibility, the Binder is sorely lacking. It takes a feat to be able to switch the vestige, and it comes with penalties. Their abilities come pre-packed in the vestiges, instead of allowing you to assemble your own list. And don't get to pick multiple vestiges until fairly high level. All this would be tolerable if the vestige abilities were powerful enough, but they're almost universally weaker than whatever type of class the vestige mimics, so you end up being a pale imitation of something else. Which, to close the circle, wouldn't be bad if you could change on the fly, but the class forces you to commit to taking on a single role each day.
All in all, if you're looking for something of that nature, the Incarnate accomplishes it better it every way. The only thing the Binder has going for it is the flavor, which I'll admit is amazing. But after playing the class I'd say it's on the weak side of the Warlock. Not totally borked, but definately lacking.