Hi there,
full disclosure: I am writing this post after another week putting work into my vault while said vault offers me, again and again and again, items which my character already wears, I already rejected multiple times, or just garbage. Thus, yes, I am a bit frustrated, but I also think that offering players the opportunity to shape their vault more actively could be a good thing, especially during the mid and end portions of a season.
I would not be surprised if someone else already had this or a similar idea: Why not enabling the player to invest some ingame currency, e.g. valorstones and/or crests, to lock in an item which they are guaranteed to be offered during the vault’s next rotation? I do not think that this should be an option from the beginning of a season, but could increase player motivation on a cross-sectional level. Also, one should furthermore have to fulfill certain criteria, e.g. having cleared the 9th Mythic+ dungeon, to be offered this option.
Make no mistake: My main character is well-off item-wise, but why not offering players more strategic choices rather than having some sort of “gacha system”? Putting in effort with no reward - or “bad” rewards, that is - feels like a slap.
And do not get me wrong: I do not think I am “the man of the people” here, but I also think that I am not alone with my wish for player-friendly improvements, because, as is, no one able to implement such functionalities seem to care.