They recently (a few years ago) introduced A* grades for 90+/100 scores, where A was 80/100 before and so, as you note, not very discriminating. I'm not totally sure, but I think a standard offer for one of the elite universities is A*AA these days.

I'm not sure I like the idea. Only having to hit 80 reduces stress quite a bit, and it gave me time to do extracurricular things like programming, and way more maths modules than anyone should :) If I had to hit 90+ in everything, I would have probably been risk adverse and cut down. It also feels like it selects a bit too much for people who over perform in exams. That said, I did have to send in my raw module marks anyway when I applied ~10 years ago, and did hit 90+ anyway.