The whole purpose in the World Cup is to determine which team is the best soccer team in the world at that current time. No team should be to qualify for the world cup simply because they are hosting the world cup. This would not serve its purpose because it would knock another team out of the qualification just because they did not get to host the world cup.
Other ways of providing gratitude to the host team could be done, but it shouldn’t affect the outcome of the games. It could even be where the location of the world cup is rotated to the different teams. Anyway, the host team already has an uncontrolled advantage. They are used to the time since it is in their country.
Some people are confused whether the host country for FIFA should automatically be qualified for the World Cup. According to the rules, the host country does get included in the list of teams that will compete for the trophy. It is given that the host country will participate because the country is investing millions of its own money just to make the event happen.
There is no guarantee however, that the host country will be reaching the finals. Remember that organizing a huge tournament will take a lot of effort. It will require a lot of people to plan how the event will take place. It is only fitting that the host country will get the chance to get the cup.