i would like to add to this. I do feel that it's too advantageous to farm with alts for dailies and always having to do it is very tedious and anti-fun. At the same time i'm afraid of more abuse if it becomes more dailies heirlooms if you straight up increase heirlooms (meaning it become even more profitable to farm with alts).
I would like to propose that an option to claim reward only with master account that would offer 3X rewards (but exclude depths to prevent overabundance of mats in endgame stuff, destroying value)- but you would then lose the option to claim from alt accounts until the next day.
This way u just farm main 5x for the full daily 15x and not have to abuse alts. Meanwhile, it does not diminish the value of alt users, as they would still be slightly better especially if u use 4alts (3x farm for full 15 claim) or 7 alts (2x for full claims). This would allow players to make a choice to do solo farm or alt farm for heirlooms and not feel too disadvantaged not abusing alt gameplay.