I agree and disagree with you.
If your texture is not a power of 2, it will not be compressed. If you texture contains an alpha, it will not be compressed. Also, for my menus, I’ve reduced the size of 2 or 3 textures while keeping the visual quality and I was able to save 1 to 2 MB easy and I have over 42 textures for the menus alone. So I know I could easily get another 5 to 6 MB right there once everything is optimized. As for my in game textures, Right now I haven’t optimized those either. They are all separate textures. I will be combining them into in atlas and I know that I will, there again save at least 2 to 3 MB. It’s little bit and chunks like this that will allow you to reduce the package.