There is a tendency to merge SP and LSA as a single set of regulations. I agree with all the above that SP should have a set of restrictions but these same restrictions need not necessarily apply to the aircraft. Just as there are GA aircraft that I do not have the endorsement or rating to fly there could be LSAs that an entry level SP cannot fly without getting an endorsement. The endorsement route is already there (gyro, seaplane, etc.) so why not add a complex endorsement?I think the Sport Pilot restrictions make perfect sense for Sport Pilots. If you want to fly other aircraft, get a Private or Commercial.
Of course, I've not heard of any manufacturers who want to go to the expense in trying to materially change the LSA standard.