A "do whatever you want" or MIT or "beerware" license may be more free for the individual, but overall it is a less free license.
The GPL *adds additional freedom* since it guarantees future revisions and public forks will also be free.
The only loss of freedom is when someone chooses to extend GPL'd software they are required to publish their code. This person loses the freedom to keep their code a secret. They are not free to withhold free software from the world.
It is a compromise. They are taking something someone else has written- if they contribute a meaningful change, the thing that would generate the most freedom would be if they contributed it back to the world, and the GPL requires this. The GPL enforces software freedom.
Fair warning- the next person that says something to the contrary in front of me is getting a lecture.