I noticed the official website of Monero (GetMonero.org) is copyrighted with a Creative Commons BY 3.0 license. Why did Monero choose this license, or choose to use this instead of Creative Commons BY 4.0?
Because the CC BY 4.0 didn't exist when we created the site. Changing the license requires an agreement from all those that have submitted a PR, so unless there's something specific in 4.0 that we want it's simply too much effort to change.
The reason we chose CC BY 3.0 is because it seemed the most appropriate to the written material, images, and logo. It allows people to share it in any way, remix it, build on top of it, modify it, even for commercial purposes. The only thing they have to do is provide proper attribution to the site, provide a link to the license, and indicate if changes were made.
Why would we want to restrict the ways in which people can use and benefit from the material on the site?