Light colored beers are pretty much the only time I'd even consider a late extract addition.
Caramelization is both good and bad (sidenote: I think in beer it's not actually caramelization, but a maillard reaction... not sure, though!). It provides much more complexity to the flavor of the beer, but it also darkens it up. It really just depends on what your goal is.
In a beer like a barleywine, you want to boil for a long time so you get those reactions - pretty much all the complexity of a barleywine is produced by melanoidins and a long aging time.
In a beer like a tripel, you probably don't want that. I think nearly every tripel I've ever seen was too dark.