This isn't the first time YoshiP has said something like this. He's said similar things during live letters in the past, so this is nothing new. This is a stressful position to be in, and, unfortunately, in a world like ours, where the internet basically raises children for their parents, he really does need to have a thicker skin or else leave reading the harsher comments to professionals.
And, of course: he talks about the Japanese comments in particular, so the same 5 or so people are pointing fingers and screeching "I told you so" at anyone who admits to not enjoying the game in the same way that they do. Predictable.
To be fair, you're ignoring at least 1/3 of their posted arguments, so you probably don't even realize what the assumptions (there were several hypotheticals, each of them depicting different scenarios) are, other than "he should get a thicker skin."
...And he should. Life is much easier to handle when your skin is thick enough to withstand the mosquito bite sting of a teenager saying "omfg this game is diarrhea shitstains swirling in a piss tea of a mom's dad-taint lolomgwtfbbq," and people who unironically put "=]" in their posts.