I don't dismiss the idea of a 'Major' being created for that 'off' year - Quite a lot of continental and community events happen in that year, not to mention world Indoors, and both Gymnastics and Cycling seem to do perfectly well with annual 'finals' - I understand that.
But i think the sell is wrong, and I think the Bienneial is probably wrong too.
This is not - and should not be suggested as -a championships, least of all the 'Ultimate' championships, a major naming mistake that undermines all their other properties, opens them up to ridicule and sells what is essentially a Diamond League final as something it isn't.
If they had called it the World Athletics Grand Prix, the World Athletics Grand finals, something that didn't overshadow the champiomnship properties, the it could have been just a bit of well financed fun, a move to create short sharp 'majors' of a type different to 'major championships'. Raxxamataz it a bit with a Gala dinner/Hall of Fame/Awards ceremony beforehand, so it feels different from the more natural drama of a champs.
One of the unappreciated realities of award shows is they rarely exist to actually give awards. They exist to bring the industry together to do business, and also to sell the industry with a facsimile of competition. WA has actual competition to sell. But there's no reason it couldn't add the razzle, make an event of it (think how IOC and EOC do this as second nature)
But not like this. It just doesn't work.