Scourge system could certainly see some clean up. Feels like they just needed to add X amount of affixes and in doing so they fucked the chances of getting anything truly beneficial for most people. Reduced Stun Threshold shouldn't even be in game, boneshatter or not, it's just fucking awful unless you're stun-locking Shaper for memes.
They should probably do a fix for similar mods like %increased fire damage + deal no fire damage. It works with weird shit like fire to chaos full convert (which may not even exist if I remember). There are some certainly amazing beneficial ones and maybe they thought they'd drown out the good shit with bad shit even though they can just weight appropriately. Stuff like +1 lightning spell skills on weapons are pretty great, but the odds of you bricking your BIS wand instead are way higher. I've seen a few good items from scourging, but mostly dogshit. The best use of it is making 6 links easily and adding resists to uniques which have none.
The suggestion that dropped Scourge items be smart rolled seems good until you hit high yellow/red maps and you're seeing literally 20+ scourge rares per map without a boss in it. Like, no exaggeration, in just high yellows I'd clear a single blood meter and have about 9 pieces of scourge rares sitting there. I get that it'd be way more rewarding if they were smart loot and make checking each item not a pain in the dick as it is currently, but it basically invalidates rares from anything else outside of delve/incursion.
On the OTHER hand, they are corrupted, so the modification of those items would be much more limited so maybe it would be alright. I personally think they just need to A: clean up shit modifiers, B: make sure you can't pair like ben/neg mods (increased fire, no fire etc) and C: make crucibled items smart-rolled. Those changes in place would make glancing at corrupts easier and give you more reason to care about the Crucible mechanic and skill tree.
My biggest issue with the league is the absolute fucking pounding I'm taking. I'm a Necro so I have minions with taunt, and blind as useless as it is, 6k EHP, ~40% block, 40% phys reduction, phasing, and I NEVER STOP MOVING and at 100-200 stacks of Scourge it's just no chance in hell. You just die. Sometimes you see it, sometimes you don't. It's brutal. I get that they did a defense revamp and perhaps I may actually need to invest in spell suppresion and try to get max block, but I shouldn't be exploding in 4 affix Tier 8 maps at level 87. That just shouldn't be happening. The Bone Offering nerf was major, but even moreso was Fortify. Between those two I lost so much safety I feel like I'm playing a totem character with 4khp or something. I honestly think they need to retune the scourge stacks from 1% per to 0.25% per. Getting 150 stacks in higher maps is nearly guaranteed if you have damage and getting 200 in Scourged maps is also a sure thing. Having mobs hitting you for triple the damage with any sort of damage mods is just too much. The Pale Angels have a 22k high end lightning spell which means that's at 0 scourge. So at 100 Scourge they're hitting for up to 44k damage before map mods. So even if you have 75% resist you're still getting 8k'd on a high end non-crit. Seems a bit much. They may have stealth nerfed them though as I spectred them last night and they do jack shit with their beams to mobs as spectres and it's widely assumed they were going to get tuned at some point.
Overall mechanic is mostly a miss, but has high end potential. Definitely didn't help get leveling rares like Ultimatum or Ritual did, but it did help level up. The new currency is actually pretty useful (mostly) when used in conjunction with the crucible or just some crafting savvy. Can pretty much 6 link any corrupted chest for a few chaos which is pretty nice.
The week one patch will probably tune down some Scourge NPCS, maybe remove some bunk affixes for scourge shit, and look to change the damage penalty of the mechanic itself.
On the plus side if you skip the mechanic outside of just clearing for exp you're not missing out on too much. Also some of the changes to Delve are fucking amazing. Really good fractured delve modifiers on items to help you craft super helpful shit. I'd just make sure to maybe hit some lvl 68 nodes for Azurite to buff your darkness resist before jumping in to depth 80 immediately or you might have a bad time.