Why is there so many figures, and pieces you CANT use for customization???

I love this game to bricks, but would’ve loved it 10 times more if I could use all of the Lego pieces in custom creation. Also, why can’t you color all the equipment and beard/skin in any color? Again, I absolutely love this game but WHY so many restrictions??? There are a lot of cool characters I could’ve made using the animal characters, or the satyr!.