This change isn't a bad thing really...
More RMT in Sea? You already have them everywhere, they don't need CoP to be easier to get access. The only reason you don't see them so much in Sea is just because the place sucks (full of RareEx items) with a broken final boss.
More noobs in Sea? Maybe, but how is that different from the whole game? You'll still need a decent Endgame LS to kill NMs, except AV, which no one can kill anyway. Make Promys and Bomb BC easier will just bring more people to enjoy a part of the game not everyone can play.
CoP isn't that hard really, just a time and money sink. I've helped my friend BLM when I still played the game, we did PM1 to end in 3 weeks, going 1/1 on every single mission and BCNM. But it requires good strategy, players, and the right jobs. Also, Airship BCNM isn't getting nerfed, so it'll stay the hardest part to access Sea, like it always been.