Check all your 12x12 paper
Before you get frustrated with what you think is a rip off, check all your 12x12. Very little of it is exactly 12x12!
Why would any company adjust to just a smidgeon smaller? Your page protectors are 12x12. You add even one layer of extra cardstock and that adds bulk. Photos and embellishments? More bulk. Pretty soon you cannot fit in your page protector!
This adjustment is not new to SU! The key is to measure and get to know your paper.