Fine, but if you count every single paint variant Yamato does than you have to count all the multiple reissues that Bandai's done over the years. Additionally, it would be unfair to discount all the other Non-Macross transforming toys the two companies have produced, or any product the two have made over the years for that matter. Lessons on how to design a type of joint or what kinds of stresses a type of plastic can handled learned from one toy are still applicable to other unrelated toys, so every product should count towards assessing the level of experience a company has at making toys (Macross related or otherwise).
In any event, the claim that Yamato has significantly more experience doing anything design or manufacturing related over bandai is an outright falsehood.
As for companies constantly updating there products from run to run, I submit the 1/48 VF-1 with it's increasingly poor finish and part fitment with every version after the 3 or 4th release.