I think the operative word there is "go" and sometimes to be allowed to "go" (aka fly in the airspace) you need the mini so its not restricted based on weight. ;)
I get the sense that a fair number of restrictions started to get set at 250g around the world,
and DJI quickly settled on 249 as their target for all Minis.
I will let someone better at physics explain the effect of mass on damage potential!
Besides, the drone you can legally fly in a foreign country is always better than the one you can't legally fly, unless you enjoy Mexican prisons! LOL!