Everything seems to work for somebody.
As Michael says, it takes a lot of work to 'perfect' a bracing system. Once you've done that you might just find that it's not as good as the 'traditional' ones, so it's hard to say at the beginning whether the effort would be worth it.
This all gets very complicated. Keep in mind that the 'standard repertoire' was written on 'traditional' instruments, and tends to work well with all of their foibles, both good and bad. A new bracing design is likely to sound different. It's likely to be 'better' in some ways and 'worse' in others, but may not serve existing music as well as the traditional system. Unless the advantages far outweigh the drawbacks in may not catch on, and even if it does it' likely to be controversial.
Much recent innovation, such as 'lattice' bracing and 'sandwich' tops, has been directed toward increasing the acoustic power of the guitar. By reducing the mass of the top that the strings have to move they can move more air, and produce more sound. Although many players have embraced these innovations, they have by no means replaced the traditional systems. There are various reasons for this, some having to do with the difference in sound, and some relating to the fundamental limits of the case. Even traditional guitars are relatively efficient, as musical instruments go, and it's hard to make substantial improvements while skirting things like 'wolf' note issues.
So, on the one hand, it's easy to see why many makers will follow the path of least resistance, and go with tradition. OTOH, any maker is also looking for some way to set themselves apart from all the others, and it's difficult to support the claim that you're 'the best' builder of the traditional pattern , particularly if you don't have a Spanish (or German) pedigree. Thus there are good reasons why a maker might want to try something different, and put in the effort to make it work at least reasonably well. Anybody can claim to be the best, but only one can be the first, and if the guitars sound good enough you might well sell enough to keep busy.