We could, but we shouldn't, because most software is crap. When the user is stuck with whatever software they got as a consequence of buying the machine they actually wanted, there's no incentive for the software not to be crap.
I think if you compare a modern car with an ECU to a "traditional" car with manual ignition / carburetion system you will find that the modern one outperforms significantly on both power and fuel efficiency.
We could, but we shouldn't, because most software is crap. When the user is stuck with whatever software they got as a consequence of buying the machine they actually wanted, there's no incentive for the software not to be crap.