I think they should have just added these minipets as drop into the Elite areas and stuff as a posible final reward instead of a mission, with not an insane low drop. As for polar bear they could have just increased the drop rate and alow it to drop at any time of the year. That way they would have increased the player activity in those endgame content and not just enter do Deep in HM once and you get a mini Kanaxai and never come back, also, the minis are gonna be so common that you probably see kamadan full of mini kanaxai. I think it was not the best decision.
As for collector edition minis they could have putted them into the game as prestigious rewards drops, and the other collector edition dances on the gw shop to increase earnings for the game.
Also theres a lot of cool skins in PvE that are just available as a green or with certain fixed stats that they could have added them into the drops with any posible atribute that was logical like: https://wiki.guildwars.com/wiki/Mallyx%27s_Creation