Well, yeah you are rooting for the pirates
think about star wars for a second?? who are you rooting for? rebel terrorist, they blew up the head government body in the galaxy, stole plans etc.
i don't know about a prequel, the problem with prequels so soon after is you have to continue to top what you have just made, if you are suggesting like in 3 years instead of Pirates 4, make Pirates of the Caribbean: early years of pirating....you have to still try and top what you just did with AWE, and bigger and better works for sequels, but if you make the prequel bigger and better, it would make this *hopefully* Pirate EITC battle, not as great because it isn't the most challenging thing these character have done...i dunno, just my thoughts
Speaking of prequels though, and how well they use old Pirate lore, it would be fantastic if in the next installment, they could use Red or Blackbeard, in saying that a prequel would seem to be the best corse for ether character, consideirng the age of piracy is seemingly ending at the end of AWE