Bottom line it can deliver greater quality at much smaller filesizes. Considering RAM and storage are more expensive per byte now than they have been in years, I think it's incumbent on everyone in a position to do so, to use those resources wisely.

WebP and AVIF and HEIC had similar advantages but also some disadvantages (honestly chief disadvantage to WebP in my humble opinion was that nothing except web browsers -- to this day -- seem to support it!).

Another important point in its favor is that JPEG XL is designed as a royalty‑free, open standard, and Google provides a perpetual, worldwide, royalty‑free patent license for its reference implementation.

Avoiding JXL (once the rollout is sufficiently complete) seems, to me, like still shipping (non-animated) .GIF files where .PNG is better and smaller.