If you take the case of Japan and SK, they have only just finished the stadium building scheme required for this summer. Its like the Olympics, it takes a lot of organisation. Four years worth in fact. Evey two years could risk making each one less special.
However, scrap the european champs and the copa america, and its an interesting proposal. You could award world cups to nations earlier to give them more time for preparation.
The worst time in life is just after a world cup has finished. Its painful knowing that the next one will be in 4 years....:depress: