Why they keep coming up with new balls? Are there a lot of politics going on with ITTF or money involved? This sport is getting worse everyday.
Tropical, we got off to a bad start, so I will try to make things better.
Anyway, I have followed this ball issue really closely from the start. It is probably some of all those things you mentioned.
DHS is a huge sponsor of ITTF. The initial versions of 40+ balls they came out with were terrible. Truly horrible,
unexpectedly horrible. But ITTF already had a deal in place with them, and most of the other companies were getting their balls from DHS (a few got balls from Double Fish, which are also bad).
Actually, the seamless balls are better (people expected them to be bad based on early prototypes, but the makers solved those problems to most people's surprise). However, the seamless were not adopted for use at any major events. At the beginning, the seamless ball people and DHS had some sort of agreement to jointly market the seamless balls, but that deal fell apart. I don't know the reason. After that, DHS had to rush their first generation 40+ ball to market. The bad quality of seamed 40+ balls from China has been an embarrassment to everybody including DHS. Apparently you couldn't just change the material from cellulose nitrate to celllose acetate, use the same methods and end up with a good ball. And also, the seamless ball makers had no powerful advocates at ITTF after their deal with DHS broke down.
Meanwhile, Nittaku came out with a new 40+ ball that most players like a lot (except for the ridiculous price). They are made of a completely new material, and they use a new technology for making the seam. All this requires new machines and processes. So DHS has been playing catch-up since then, but may finally be about to come out with something decent.
Some of the politics people can only speculate about. DHS for sure has a lot of power at ITTF, though. It is also a fact that the factories that made the old celluloid balls were dangerous. I had read somewhere that there had been some large fires at Chinese factories, and people had been killed. The problem is that there was really never a compelling reason to rush it through before everything was in place. ITTF thought it would be easy to change, and it wasn't. The whole industry could have settled on a single standard and then change the ball rule but ITTF thought it was better to get 40+ balls out sooner and then let things settle out (this from interviews of ITTF people responsible for the decisions, some of which can be read at OOAK Table Tennis forum if you search back a few years).
But it is possible that,
if this new DHS ball is something kind of like the newest Nittaku balls, that things will get at least a bit more uniform. BUT, if it is something qualitatively different from everything else out there, things may get worse!
Funny thing is (actually not funny at all) but "funny", every time ITTF makes a major rule change, prices of equipment go up rapidly. Happened after 40 mm balls came up. Happened dramatically after the speed glue ban. And happened even more when 40+ balls. One can't help wondering about this.