I don't think it's idiotic on a business standpoint especially on a big company such as Bandai with lots of different lines/IPs. As others already mentioned, production capacity is most probably allocated / budgeted for example for this figure in advance for a set number of production quantity. Obviously the amount they set is something that would be profitable. They need to define a fixed amount since that same production capacity allocated might be used for another toy/figure line in their schedule. So if that's their production flow/schedule, and if their production schedule is tight, then a variable amount of figures to produce can mess up their production timeline which might also affect the production of other figures/lines.
They can also set the amount to higher numbers. However, Japanese Companies are usually risk averse so I believe they're content with having a modest profit as long as there's no excess or unsold inventories or production capacity wasted. I would assume that if they decide to a higher amount of figures, then that would mean more production capacity allocated for that figure. Now, if the orders don't meet the said quota (lesser orders), I don't think they can just easily change their production timeline so that they can use the unused capacity for other products. Changing production timelines, requires significant man hours and resources to make the changes. They can choose not to change it, but again, the production capacity is wasted which also translates to a loss. So I see that they would want something more consistent with regards to production. Additionally, it's also possible that their schedule is just that tight, since Bandai produce/release a lot of lines or some other lines are more profitable so they have priority in production.
Another thing, is that their amount quota most probably reflects the Japanese market only or maybe includes the few places in which p-bandai or tamashii web is available. So those are markets that Bandai wants to cater for this particular line. Unfortunately, we are not that market, so we're excluded to any quota planning, etc.
It sucks for us, but I think what Bandai is doing is just good business sense.