Both are very muscular and look like bodybuilders. Yeah, the Arkham build is slightly more ridiculous with the forearms but that's due to the medium and the engine used for the Arkham games (look up Gears of War).
The overall effect is the same...both are quite swole, and the difference between them isn't big enough to call one "ridiculous" and not the other. If some brought the Arkham Batsuit to live-action, it would look quite similar to the Snyder suit build-wise.
I'd also add that Batman's body in TDKR, which heavily inspires Batfleck, is just as, if not more, ridiculous as the Arkham games.