eXtremely Late to the party: JPEG was so preoccupied with trying to generate revenue streams that they were totally blindsided by WebP/AVIF which made "generate revenue streams" an explicit non-goal.
JPEG XL is a royalty-free codec and "generating revenue streams" was never a goal for the project. You can see this already in the very first draft call for proposals from 2017: https://jpeg.org/downloads/jpegxl/jpegxl-draft_cfp.pdf
(see section 5 on page 7)
Which is my point: "JPEG XL" is "too little too late" after JPEG tried to monetize its brand with various other, pretty much failed initiatives:
- JPEG 2000 is popular in the medical imaging space but everywhere else shunned like the patented abomination it is until the patents fizzled out.
- JPEG XR is covered by Microsoft's patents that are supposedly defused under a "covenant not to sue" (but not really).
- JPEG XT builds on JPEG 2000 with all its money-grubbing problems.
- JPEG XS is a pretty particular beast regarding its use cases, but nevermind, there's a patent pool. As such it won't become popular before 2040.
Only with JPEG XL (2017) did they _finally_ acknowledge that they're working on standards that everybody avoids to the best of their abilities due to the licensing situations JPEG optimized for. 20 years for naught.
At that point WebP (whose ancestry makes it explicitly a part of the "avoid the patent mess" movement) was already out for 7 years.
JPEG and JPEG 2000 were based on the principle that the core codec was royalty-free but there might be patent-encumbered optional things (such as arithmetic coding, in the case of JPEG) that could be just left out if you want a royalty-free codec. Eventually it became clear that basically a de facto standard would always emerge that just skipped the patent encumbered things; JPEG XL doesn't have any (known) patent-encumbered ingredients for that reason: it's a bit pointless to add things to the spec that nobody will want to use anyway.
I don't think patents played a big role in the (lack of) adoption of JPEG 2000 and JPEG XR; more likely, in my opinion, the main problem was that good FOSS implementations were not readily available at the right time. The core codec of J2K has been royalty-free from the start, but it took quite a while before good FOSS software (like OpenJPEG) was available. Computational complexity was also an issue in its early days.
For JPEG XR, even today there is no well-maintained FOSS implementation available; this is probably a bigger reason for its lack of popularity than potential patent issues. Compare for example with h264 (and x264), which had more substantial patent issues but nevertheless became very popular.
JPEG XT builds on JPEG, not JPEG 2000.
JPEG XS has a very specific niche use case (ultra-low latency, as a mezzanine codec for video production workflows), it doesn't have the goal of 'becoming popular' as a general-purpose codec.
JPEG is not MPEG. While both are working groups of ISO, which does have a policy that is not exactly "avoid the patent mess" but rather "don't talk about IP", there is quite a big difference in membership composition and attitudes between those two groups. Having a royalty-free baseline codec (and more recently, having just a completely royalty-free codec) has been something JPEG has been pursuing since the beginning (1980s), while in MPEG they're only recently coming to that conclusion (with EVC, no doubt due to pressure from initiatives like AOM).
