Well, it being based on a weekly base for 1 primal wouldn't really break the game. It would still be in 99% of all cases stuff like Nutracker, Goldskin, Blackthorne's, Kymbo's Gold, [...].
The list of "15 Free Forgotten Souls"-Legendaries is long, the chance to get any of the wanted ones is much smaller than any chance of those "15FFS"-Legs and even if it is one of the more desired ones, it still does not have to mean that it is one of those that >you< desire (for example, got [Shadow's Mantle DH Boots]. It's "15FFSs" that I'll never salvage but also rarely if ever make use of :p Can't get myself to really like it).
Because of that I'd actually almost claim that those "Primal Rifts" would be more like a waste of time, cause if it is meant to be like <5 different challenging bossfights> , it should neither result in:
a) Mindless "Bane of the Stricken"-stacking till it surrenders, ...
nor b) in a situation of "Look, that Necro overkills each boss with his Trag'oul/Pestilance burst - lel, 4.3sec of his 10sec."
(Which is more than realistic with decent gear for those sets and an average Paragon-Level.)
It would have to be 5 different bosses, tuned for custom-made characters or with some damage-in-/output algorithm to adjust the numbers of different people on the same spec on an atleast compareable level to make it somehow "controlable" instead of freeloot for chosen ones, riverlong threads for the least chosen ones.
AND THAT ... would take human resources to tune. On top of that, either it is the same 5 bosses each week, so after the first time you did it, it's gonna be 1234-Rinse-Repeat-WeeklyContent, thus after time even less challenging than those "Challenge Rifts" *cough* or it would take even more human resources to work out even more bosses that all have to be tuned for different classes / get those magic algorithms to prevent total outliners.
I can understand the wish for something like a bad luck protection----
(which this would be kinda - in case you didn't get any other Primals this week, you will atleast get this one like everyone else - as long as you beat the challenge)---- but looking at the amount of work Diablo3 is given nowadays, something like that would either be a "flop" with a free Primal for everyone (literally, least amount of encounter design, copy-paste gameplay to outlast the bosses etc.) or the reason why we would not get any change to current flaws, less input for proper number tweaks and so on and so on.
Current flaws I'd call for example: The pain of those new added maps, again and again and again...
Newly added map, does right exactly that again.
Newly added map, surprise
Getting a real pain when you start into those festering woods with an A Cappella of 30 Soul Lashers saying hello, not one elite close by to justify triggering CDs right at the door just to get out there/survive it/or even beat it for a minimum of progress - any of the 3 resulting in downtime or even active cheat death passive timer sub 00:10-15:00.
Or that Triple-BigSquareLayer-Map for normal rifts that has like 3 elite somewhere on it - if that would be per layer, that would be ok , but like 3 packs for 3 big layers - often those 3 even clustered somewhere while every speedbuild that relies on In-Geom literally walks through medium amounts of common enemies, finally reaching the third floor to find all 3 packs close to the exit ... well, and that for like 20-30% progress.
Those every-day things should take less work and would really improve my daily experience from playing D3 :p Having a weekly cooldown for a Primal and then getting Goldskin, I'd most likely throw my apartment out of the window - right, my apartment, my screen already waiting down there due to getting twice the TripleEmptyLayer-Map in a row, on 5 out of 5 rifts each.xP
I really don't want to /bash your idea simply for being there or else, but they would really take far much more elaboration and would be almost impossible to balance for the 7 classes with all their different sets and all. And balance between the classes on that challenge would be much more important than vs. [Random RiftGuardian] since those bosses alone would be the challenge, not the Rift as a whole / the average of several Rifts at LevelX. Too much work for something that people would do once per week.
P.S. Wrote more than I actually wanted, well updates on my actual computer, nothing good @TV, ... sorry
I would like them to overhaul the crafting system and make some kind of new crafting mat that requires tons of mats or rare mats or some kind of conquest-like challenge to get the mats, once per week that would allow you to either upgrade an ancient to primal, or at least have option to choose a specific item type and have the game roll a primal for it. Example: you get the mats, and now you choose daggers, the game then poof gives you a random primal of dagger type.
this would be nice to get a little more bad luck control, and not saying getting the mats would be easy, maybe make the requirement doing a 90 solo, and like require 100 souls, 1000 of each mat or something on top of that.
This would make it not available right away in a season, at least for first week or so for those elite players, and have something else for players who take their time to shoot for, and then look forward to rolling it each week, even after you have finished your normal build.
They should overhaul the crafting system to make gear that scales with your level, like heirlooms in wow, that grows with your level, special gear that as your paragon grows, your stats on the gear grows or something.
They have so many options, and there's so many good suggestions on a daily basis that could be done, but we get...s12..now with new wings...enjoy!...i enjoy the game still but its extremely stale/old now, harder and harder to log in each season, the ONLY reason i even am playing s12 is cuz of the buffs and updates to old builds, and its amazing...but what then for s13? will be it s15 before we get another massive buff?
Lastly...buff drop rate or alternative way to get Ramha's Gifts...i'm para 430 have yet to see a gift drop, people saying they are 700+ never seen one...insane disparity for that item when you need them on a regular basis, they shouldn't have that huge of a drop rate difference, some people get 10 in a few days, others NOTHING for WEEKS...i understand rng and luck but that item specifically seems to just be an oddity, went weeks without one last season, then to have them drop like candy for a week, then nothing again rest of season...intended?