Yes, steeplechases are dangerous, and horses are sometimes badly injured - but so are jockeys, and they continue to do it. The horses, like the jockeys, are volunteers: you couldn't force a horse to race if it didn't want to, and, since many humans enjoy extreme physical exertion with an element of danger, it's reasonable to assume that horses do, as well. Therefore, don't ban it, and also don't over-regulate it, though some regulation is no doubt necessary.