Current layout of motorcycles is not an accident or a whim. It’s a result of decades of tried and tested variations until engineers found a good and robust solution. Honda is especially one to note there with their kaizen manufacturing method where each iteration is improved if possible by any worker. Also, believe it or not, there was an ICE motorcycle with engine mounted on front wheel. You couldn’t break with it, because it didn’t have clutch and gear. So you just choke it out.