A: Because your mech's ego isn't inflated enough already. Seriously, it's not like we haven't told you before: buying parts will give you a +5 to your mech's combat effectiveness. But don't just take our word for it, ask your mech.
We recommend the following:
Don't forget, buying parts is a serious business. Consult your mech's manual for more information.
We understand that your wallet might be crying. But let's be real, you probably won't live to see next week if your mech can't afford the good stuff. Just ask your mech if it has any spare cash lying around... just kidding, that's just not how it works.