I see the current A* as an O level/early GCSE A grade, top grade is top grade, work out how much it means by looking at the percentile that achieve it.
Pupils are supposed to get better year on year as each generation of teachers receive a better eductaion. If you gave a GCSE paper to 16year olds from 100 years ago their average grades would have been diabolical compared to currently. Give the same paper in 100 years time and I would hope that standards have moved on much further with newer teaching techniques and equipment leading to even better teachers, human or not, meaning most pupils should get an A/A* grade with the current grading system.
Agree about the inclusive papers at GCSE, whilst in mandatory education all pupils including the less advanced should be allowed to show what they have learnt, otherwise whats the point of submitting them to the exam, even if that means a paper that is less challenging to the brightest pupils. A-level and beyond is where more advanced pupils will continue to learn and show they can apply that knowledge in an intelligent way rather than being walked through an exam.