That's interesting. The piece is now in the DipABRSM syllabus (it's also in the ATCL syllabus).
Similar things have happened with other pieces. I remember when I was doing my Grade 8 in the 1990s, one had to play the whole of one of the following Beethoven sonatas: op 2 no 1, op 14 nos 1 & 2. These three sonatas are now DipABRSM pieces. I'm sure that doesn't make it any easier to pass the DipABRSM but one does wonder whether they have lowered the technical requirements for Grade 8.