You mention a lot of vanity mods that can be performed, and I agree many of those are harmless and cosmetic. Sure, there are probably a ton of cosmetic and basic, safe mods that can be performed to your vehicle. To the best of my knowledge, there are lots of regulations that automotive parts are required to adhere to. You are talking about buying pieces that have been manufactured up to whatever standards have been set as required. Do you think we will have the same standards placed on the firmware and those who are hacking out code for this?
I'm all for freedom and love to tinker and mod devices. It's fun, most of the readers on this site likely do the same. What I take concern with is the fact that any idiot can anonymously dump faulty firmware onto the internet and start causing wrecks and injury to other drivers. Perhaps I'm wrong, but if someone manufactures tires and rims, they are probably going to be a lot easier to track down and hold accountable.
Now, on the less extreme end, if there was a NO_SPEEDING flag I would gladly change it. However, I can't picture myself driving any car that I have no control over. It just sounds like a terrible idea.