This has been going on for years, and several Cup regattas. Why the squawking now? Two Cups ago Spithill was racing for Luna Rossa (the Italians), I believe it was three Cups ago that the Japanese team was filled with mostly members of the New York Yacht Club. Russell Coutts basically just goes to the highest bidder, whomever pays him most. Suisse, US, wherever. Zero loyalty to his nation if you listen to the Kiwi fans. Currently the most top sailors are from NZ and Australia, thus they fill up a lot of winning teams. Years from now this will probably be other countries, and most will still race for whatever "country" they like. This is how it's been for some time, and it's not going to change.
Overall, I'd say this has to be considered one of the most exciting Cups in memory. Many of the races were close, and the cats were thrilling to watch at that speed. This may have also given sailing a needed shot in the arm. Certainly after the 2012 controversy, and 1995, 2000, and 2003 blowouts where one yacht/team was clearly superior to the others.
As to the winged keel, that was an incredible regatta for those who remember. Dennis Conner had brilliantly sailed to a 3-1 lead in a disadvantaged yacht, but failed to secure the win. Very dramatic. Sailing fans may remember his 1987 Louis Vitton cup win to get to the America's Cup finals in five thrilling races, outsailing a superior designed NZ yacht, Kiwi Magic and skipper Chris Dickson - who had gone 37-1 in the round robins, beating Conner twice.