I understand those finding these costumes tasteless. But calling them an universal act of pedophilia simply lacks ground in more than one way.
From an arctistic point of view: If you just look at them, they are stilized human beings. It's really in the eye of the beholder whether they are considered under 18 or above 18. You can't call out anyone on such a subjective basis.
Then there is the problem of drawing the line between pornographic and non-pornographic content. Both from a legal and ethical standpoint. I believe people in bikini, or revealig costumes isn't pornography. And in western society it is not really pornography legally speaking either. You might have a different oppinion, but once again too shaky ground to condemn the art on.
And when the content is not legally pornographic it comes down to cultural preferences and regional differences in law whether it's appropriate or not. Looking at the legal side of things; take my country for example: the age of consent is 14, thus even though pornographic content of people under 18 is strictly prohibited, you are free to be sexually attracted to people above 14 (though therein also lies the problem of differences between what's morally and what's legally right). So in this case, even if you believe the original Japanese ages are the "real" ages of these characters - the ease, with they could change them in the translation process proves in itself how arbitrary they are - you can't call anyone from this country a pedophile IF they are aroused by these pixels thus you can't call the content inappropriate in any objective way.
To sum up: IF you believe these characters look child-like, IF you think they are actually underaged, IF you believe people in cleavage is bordering pornography, IF art like this is morally/legally wrong in your region only then you could tag it as inappropriate. However, this oppinion can't be universally "right" on such shaky grounds. And most certainly forms no basis to call people enjoying the content pedophiles.
(This whole wall of text only stands if we don't narrow down the discussion to the NA version of the game. The same changes are present in the EU version as well, so I felt it can't be left out from the debate.)