I also have only 2GB left and no issues. A lot of us fill it up. What's the point of buying a 128GB device and leaving half of it empty?
No one is saying keep 50% free. You do the math, 10% is 12.8 GB, a nice healthy amount of space for over the air updates and decompression. Have fun when iOS 9 comes around the bend. It's really in your best interest mate.