This is the only answer they have ever given to this question:
https://forums.galaxy-of-heroes.starwars.ea.com/discussion/205068/developer-q-a-may-29th/p1
Q: Will you ever add multibuy to bronzium data cards?
A: CG_Carrie: There are no plans for this. I think we get this question at least a few times a year, but the short of it is, when ally points were used as the currency in the old Tournament system, that was a big mistake that we made. When we turned off Tournaments, we didn't feel like we could take away the currency that was granted, even though we didn't want it to be used to open Bronzium packs at that amount. We probably should have then, but instead have decided to let it sit, and find other ways for you to spend large amounts of the ally points via the weekly shipments. NR: We'll likely try to find other ways for you to use large amounts of Ally Points on something that's meaningful for where you are in the game.