So I see many posts about Duriel and boss mats and UBER problems and wanted to post these solutions.
These are the changes I would make:
1] All boss materials go to the material tab. No more clogging up inventory. No more duping.
2] All bosses have a timer you can summon for free. Boss mats let you summon bosses that their timer is on cooldown. Very simple. A sort of compromise solution from the ppl that just want them free all the time.
Duriel - 24h
Varshan - 12h
Other - 8h
3] Completion of the entire season journey to 100% completion gives 3 sparkles.
4] UBERs now have cosmetic alternates to function as chase items. Each UBER has a 5% chance to drop as the cosmetic alternate. This gives a reason to go for ubers even if you have them all. Alternate cosmetic ubers cant be crafted and give 2 sparkles if salvaged.
5] UBER drops from Duriel now have bad luck protection. IF you have not got an uber drop after 100 Duriel Runs your next run will have a guaranteed uber. There is no bad luck protection for UBERs outside of duriel.
6] UBER pool is expanded. Each hero would have access to 8 any class ubers and 2 specific class ubers.
Some ideas → Top 10 
UBER Uniques - PC General Discussion - Diablo IV Forums (blizzard.com)
7] UBER Goblins are added to the game. These goblins always drop at least 1 unique with a 1% UBER chance. They are very rare. These goblins are teal colored and ubers are changed to have a teal glow instead of same glow as uniques.
8] Bad UBERs are buffed like Ahavarion and Andariels Visage.
I made a post on this.
Petition to update Ahavarion, Spear of Lycander 
- PC General Discussion - Diablo IV Forums (blizzard.com)
Proposed Alternate affixes for Andariel Visage:
All stats
Haste (Haste is a new affix that is attack speed and movement speed on one affix)
Life Steal
Lucky Hit Chance (poison resist removed. This gives more synergy.)
+3 to all poison or shadow skills (additional ability)
Lucky Hit - 15% chance to apply a poison nova over 5 seconds.
Lucky Hit - 15% chance to apply a shadow nova over 5 seconds. (additional ability)
9] Duriel no longer drops UBERs for ppl in your party. Only those adding mats to the summoning thing can get ubers but others can get 925 gear. Then the droprate for ubers is increased to 2.5 or 3% compensate for the fact these will no longer be run 24 / 7. Duriel was never meant to be run 24 / 7 in endless rotas. This also helps solo player and puts RMT 99% out of business as they cant sell boss mats or Duriel runs for ubers.
10] The cost to turn sparkles into an UBER is now 3 to 1 and not 5 to 1. 5 to 1 was bad. We all know it. 3 to 1 is proper amount.
11] Mini Sparkles are added to the game. Salvaging a unique gives you 1 mini sparkle. 100 mini sparkles give you 1 sparkle. This in essence makes it so that getting 300 uniques to drop will give you an uber you want. Other things could be added to the game that drop mini sparkles as well such as a mini sparkle helltide chest or something.
Other uses could be added for mini sparkles as well such as a free enchant roll.
This is a pretty good list of changes right? Right? RIGHT!!?? 
+1 if you think so! 
IF not tell me why u no like.