I think license depends on your goal. If your goal is to create a web image format.. you need all the browsers to agree to include you. All browsers will not add a GPLv3 image type. Therefore it is dead before it launched.
No, that's backwards. Microsoft and Apple and Google prevent the usage of the GPL/LGPL. Don't blame the GPL for the bad behavior of large corporations that are using their immense power to try to stop copyleft.
