Why is Angry Birds 2 asking for all these permissions?
Depending on your device's operative system, Angry Birds 2 may prompt you to grant the game access to your photos, media and storage. I't only the 'storage' part that we're interested in.
The reason the game needs access to your device's storage is because of application size restrictions before downloading the game. This means you may have to download more files in order for the game to run properly, and this requires Angry Birds 2 to have access to your device storage.
This means Angry Birds 2 needing access to your device storage in order to load that second file which will allow the game to run. If you don't grant the game access, it will not be able to load.
Why doesn't the game work if I deny the permissions?
If you deny access to your device storage, the game won't be able to load the files it requires to run. In this case, you won't be able to play.
If you have denied this permission and clicked "Don't ask me again", you will need to manually allow the permission from your devices settings in order to be able to play.
Please note that Angry Birds 2 will never access the personal files on your device. The game will only have access to the game files.