Tapu Lele is the main selling point of Guardians Rising. This goes with Shaymin-EX. If they release a Tin or a Box with Lele or Shay in it they will get a quick surge of sales, and then when the box gets sold out after initial distribution there isn't as much money left for them to make with Guardians Rising sales. If they don't release a box they can milk the 6$ CAD a pack for the next two years and make lots more money off that. Theyre a business first and competitive game second. Where they can max profit they wont put anything in the way that could damage that number. Tapu Lele is guaranteed to keep Guardians Rising sales super high and a box would damage that.