I think you guys misunderstand the Pilot Skills. After you unolck the skills, it allows you to use modules devoted to those skills in your mech. Mechs have a limited number of module slots. Pilot skills are not giving you passive bonuses, so it doesn't matter if you have every single one of them learned, you're still tailoring your mech based on what modules you want to use, you just have a larger pool to select from. All pilots might end up being the same at the end, but what modules they take could be vastly different. That's where the variation comes in.