Tomasz-
There seem to be consensus to apply that.
A consensus of one, I presume.
Warning to certain people: some Polish Wikipedians want to change default skin too, and there's nothing non-Polish Wikipedians can do to stop it, would consensus on it emerge among Polish Wikipedians.
If the project leadership decides that Wikipedias are not allowed to change their default skin, they are not allowed to do that, and any change to that effect will be reverted. If, however, the project leadership approves of giving each wiki the right to change the default skin, this is indeed a choice you can make.
Regards,
Erik