While this would be the fairest option this is never going to happen, if I am not misremembering there was a time in which the world cup champion was also given an automatic qualification to the next world cup so they could defend their championship and later this rule was abolished, and in theory it would make sense for the host nation to also be forced to qualify on their own, but this is about money, and if this rule was abolished all host nations on their bid to win the rights to host the world cup will ask for automatic qualification anyway.