It is because you can’t create an account anymore on spiffy360 wii and you need an account to download them. It would be a real waste for them to not be accessible by everyone. If you read closely the description I credit every themes.
Here’s the thread where we discussed about it : https://gbatemp.net/threads/spiffy360-down-where-can-i-get-usbloadergx-themes.525933/
Rotflmao 
Reactions: Chary