This is because Hiroshimafu-okonomiyaki puts far more amount of vegetables than that of Kansaifu-okonomiyaki, is less likely to be cooked because of thickness and thus the low heat in the household can not extract water from the vegetables and so the finished one is watery, a bit of skill is necessary for turning it over, and the iron plate, which is wide enough to be able to grill the dough, soba, egg, etc., at the same time, is necessary.
関西風と比べて遥かに大量の野菜が入り、また分厚くて火が通りづらい広島風の場合、家庭の低い火力では野菜の水分が飛ばずにべちゃっとした仕上がりになってしまうこと、ひっくり返すのにも多少の技術が必要なこと、生地・そば・卵などを同時に焼ける広い鉄板が必要なことなどがその理由である。