I guess you could make that argument, but I think what they did to Bucky actually improved the story, because the thought of sending a kid to war as some quirky sidekick was always messed up to begin with, and made Steve look really bad. There was nothing that weird or problematic about Joaquin's origin story that required such a change. They just did it.... because.
Yeah, but I think he's still considerably younger than Sam in the MCU, even if he's older than he was in the comics.