You can use the same Bose headphones with your MacBook, y'know, and they aren't any more a modification of the MacBook than they are of the Accord. You can also plug in external Thunderbolt SSDs that are effectively indistinguishable from an internal in terms of speed. Your analogy kinda falls apart there.

But if upgradeability and replaceable parts are your #1 concern, then...yeah, you're not in the target market for a Mac laptop. So that means that it's unlikely you'd ever have been looking at having a Mac be your primary machine in the first place—if you needed one to do development on, it would be a secondary machine, where you'd probably set up your dev environment, check out the code, compile it, and test it, then go back to the computer you actually enjoy using for the rest. Maybe look into a Mac Mini?