As a concession from my opinions stated earlier, I suppose an alternative to the RNG based grind would be to make the atma/alexandrite drop easily from bosses etc, but add a lengthy (high) number of requisite tasks that also need to be completed. Say, 400 fates or something like that to "charge" or activate those atma etc. This way it keeps with the developers vision for this content to inject life into the low level content for new players, but also allows players to know exactly how long they need to grind for. The way it is at the moment, some players got all their atmas in just a couple of days, yet others got nothing for the same time spent.
