After 2 full expansions of M+ and now in Shadowlands… One thing that I really miss about early Legion M+ dungeons is the multiple chests at the end of a run if you beat the timer in a good amount of time.
So I think it would be nice to bring back Two and Three chests, especially for the fact that even to this day, people still call beating the timer two or three chested due to the legacy and impression these early Legion runs left on people.
Especially in a world where Blizzard has become stingy with loot, multiple chests can at least bring a little bit more sense of reward, even if all we get is anima, at the very least, allow each individual chest contain a pathetic 35 anima reward.
Its not a bad idea, but there would be little point.
The loot that drops from keys is near useless past the first week of gearing or so, so no one needs more of it, really.
The bigger thing that is missed here though is that the timer and functionality of “upgrades” was also changed.
At the start of Legion, keys were balanced around being able to multi-upgrade them.
Like in Challenge Modes, where the goal was gold, not bronze.
The goal was always three chesting, not just upgrading.
That is no longer the case, and very few double upgrades are accomplished at a real level.
VERY few triple upgrades even more so.
I would not say no to them bringing it back, but it would be basically pointless given how rewards from M+ work right now so I basically wouldn’t care at all.
I love the number of people I’ve had ask me why it’s called “two chesting” or “three chesting”… I’m like, I’ve been playing this game since 2004 and THAT is the question you choose to make me feel old? 
(Honestly, it IS funny people who have no idea why it’s called that keep calling it that. 
)
The reason for this isn’t that BFA or SL dungeons are harder to 2 or 3 chest, it’s because there are less people who are running lower keys who are overskilled for them… However with the multiple chests in Legion, this pushed people to run slightly lower keys to 2 or 3 chest them for more opportunities at loot as opposed to running a higher key and only getting 1 chest and just having just one chance at loot. This also had the benefit of helping out players/groups with these lower keys, as often in Legion you may have a god-tier dps, healer, or tank join up to your +4 or whatever key well below their paygrade and helping your group 2 or 3 chest it
Regardless if this is only a subconscious thing.
So this is another reason why I believe multiple chests need to return, it benefited more people than the current system, especially with how it helped out those who are stuck in lower keys as it opened the doors to more people joining their group who would virtually guarantee or increase the odds dramatically that it will be completed on time or be multichested.
and this is how you know a player is a Legion or BFA baby when you butt in to the conversation and correct them and point out this started with Legion (2016) not 2004 
I wasn’t correcting them, hence the: “and THAT is the question you choose to make me feel old?” There are so many other questions to make you (a player) feel older.