I think the loosening of rubber colours is good, although I don’t agree to the ITTF’s changes very often.
In the first place, there was no any limit, including the black one. Then the red and black came. The people didn’t like it very much, but it was reasonable because the twiddle of rubbers with different functions. It made the games unfair.
However, today those long-pips and anti-spin are on the wane due to the big ball policy. The red and black limit is out of date. It’s time to let the consumers have more choices.
In the past, it seemed some models had single colour, some two or three. Believed those manufacturers could find their ways to avoid the inventory problem.