It doesn't really bother me either, but I can see how fans might be bummed. While not a full origin story, it's clear that the 4 are still relatively new- maybe only a year or two old at this point. Ben is probably still coming to terms with his appearance and how he's portrayed by the media, and methinks him finally saying the catchphrase (we all know he will eventually) is him coming to terms with how he looks now. It's not gonna be an "Avengers, Assemble!" moment, nor should it be, but I think it's kinda cool that they're allowing the line to have some weight to it, and not just some quirky thing he says because he's a New Yorker.