Actually, radially laced wheels are very strong laterally, which is why many flatlanders tend to use them. However, the problem is, because they are not crossed, the spokes stress is put on it near the hub and is not distributed around the wheel as much, so if you were to do a massive drop to flat, you would stretch some while compressing others and most likely get a real bad hop in it. Also, you need higher spoke tension, which puts more stress on the hub and can cause cracking and breaking.