The Ironborn are the major addition to the franchise that I think Martin overindulges in, but he seems to really like them, moreso than I do.
Really, in terms of AFFC/ADWD, the POVs can be loosely divided into those characters whose stories really necessitated the scrapping of the five-year gap, and those characters whose stories would have accommodated it just fine.
In the latter category would go Jon and Dany, especially, as well as arguably Cersei, and characters like Stannis who are not POVs but depicted in other POVs. Those characters are dealing with very immediate threats and/or engaged in active rule. Cersei is going nuts (or more nuts than she already was) and destroying the Lannister regime; Jon and Dany are trying their hand at real sustained leadership, which is harder than it looks (particularly in Dany's case, where her story shows how she was good at inspiring people and conquering, but had no idea how to deal with the aftermath).
Then you have characters who could easily have skipped five years and updated us on what had happened to them in the intervening space. All of the Stark kids fall into this category, for instance, and so their chapter counts tend to be fairly low -- except Arya, and Martin has gone on record as saying he just really likes writing about Arya in Braavos. I'm not really sure that her greater chapter count tells us that much more than "Alayne" or Bran's 3/4, though. Tyrion also falls into that category -- his chapters are really the ones that could be most easily trimmed.
Then I guess you have a third category, groups of POVs that serve to introduce new settings and characters. And earlier poster is correct that, strictly from a plot perspective, you didn't really need that many Dornish chapters; but the goal there was to introduce the Dornish setting and characters are really get a feel for them. Same with the Ironborn.