Definitely far from useless. They are definitely more powerful, and the only changes were mechanics.
-Trade Nation: One of the civs that strives in the Ancient - Medieval Eras with the ability to settle new cities across the globe and gain access to many civs before others. Placing settlers around spots offers trade with many nations which is a great diploma boost too.
-Culture and Tourism: Culture Victory benefits a lot more from Wide civilizations than before. Building new cities to store great works. For Polynesia, well-planned and well-placed cities offer large culture boosts. Also, these Moais benefit from brand new buildings: Hotels and Airports. Unlike most other culture civs, Polynesia can augment their tourism without great works. Tourism becomes important in the Atomic and Information Era. Most likely you'll lose the wonder spam to another civ, but as long as you obtain Great Lighthouse and Colossus, you're set. If you choose a Culture victory, bypass the Printing Press route and chase Archaeology. You'll know the location of many spots. I found with Internet tech, you're hitting 700 - 1000 tourism.
-World Congress and City-States: Early access to all civs and a decision to pursue Printing Press, gains first access to hosting. Having access to all civs around the world first gives the chance to improve diplo status via trading luxuries or settling cities for trade routes. Having access to every city-state early gives an advantage to snowball your influence in completing quests. More often than not, more than 4 civs share a quest giving you additional delegates in further eras to hold onto host. Abuse the WC to give you an edge banning luxury resources. In BNW you can't be friends with anyone, so choose your allies and choose your enemies, and solidify those friendships as the WC host. Moais, Haka, and water maps give you a nice means of tutting against civs not enthralles with your diplomatic, espionage, or ideological successes.
End Note: Polynesia is not a top-end civ since its specific towards large water maps in which they are freaking overpowered with. Polynesia isn't an easy civ as it gives you tools and not crutches. However, creative players can use these tools to craft their world.