Right, but for everyone else there is still the losses- planes and navy add up. A vast majority of players know better than to keep cm's on hand so that part is useless for most.
Also the nuclear anarchy reduction is a nice help, also depends on how much back collecting your at- unless you have the advantage of declaring and collect before going into battle.
As the index says:
Therefore national wonders are not intended for everyone and are instead intended to provide a slight strategy for the most advanced players and an additional goal for everyone to strive to. The following are the official costs and bonuses of national wonders.