This is a great idea. I've said for years they should do this, but I said they should use 1989, the year random testing was introduced, as the threshold. This is even bolder. Many clean WR holders, sadly, will have their records taken, unfortunately.
But it's for the best in the big picture. There is going to be some really weak WRs, men's LJ leaps to mind. I think it will be Saladino?
The clean record holders like El G, Powell and Radcliffe who may gripe can still boast of being a world record breaker, just as if anyone broke their record on the track. But this is a good time to reset. When FAT timing was instituted the old records became obsolete.
This is good for the sport. Glad Coe is doing this.