You can't just judge Aerts on the tale end of his career.
Aerts was a prodigy. Youngest ever K-1 champ (23), first two win two GPs consecutively, holder of record for the shortest run up to the title ('98), and all this he accomplished when competition was at its height and he himself was drinking and partying. On top that already superstar career, he has the longevity accomplishments. Full attendance of all WGPs from '93-2010, defeating the #1 HW first in 1992 and last in 2010, WGP finalist in 2006, 2007, 2010.
If anything, Aerts is like Ali. Superprodigy that everyone wrote off but still managed to be competitive to the end of their career.