I don't see those pros and cons. Before you had a load of buttons that you were pressing just so your tank could avoid tankstance because nobody liked tankstance. Lucid, Refresh and Tactician were ok because they added something else to the package while Diversion was something that you just pressed prepull and then kept hitting every 2 minutes just because. Then there's poor SAMs and especially MNKs who initially had only Diversion but got aggro dumps that literally cost them their DPS resourses. Then when someone doesn't use them, you as a tank are just screwed. If tanks don't want to be in tankstance as it's both worse and boring while these buttons existed only so tanks can not go into tankstance then removing both just seems like a pretty good idea to me.

To top it off WAR and NIN were already otherwise in really good spots but to top it off WAR could Unchain the huge downside of tankstance on pull and switch into DPS stance off GCD while NIN could provide them extra aggro while suppressing the top DPS or Healer aggro generation to boot. More buttons that you're pressing just to not have to deal with aggro combos or sitting in tankstance. While I'd say NINs stuff was at least flavorful, I don't miss any of these buttons at all.

In an optimal setting you barely used tankstance or didn't use it at all and nobody draws aggro. Makes perfect sense to me to just make the change where nobody has to use old tankstance and take all the aggro related button bloat out.

Homogenization or WAR & DRK boring rotations don't really have anything at all to do with the aggro change.

I also don't really see how the old system "can help new players" while being "scary looking for them".
People still losing aggro isn't really something you can list as a con as the only way to fix that would be to make tanks automatically get all aggro. That's like listing people watching Netflix while playing as a new con as if that wasn't happening before. Not to mention people lost aggro before way, way more than now. Now it happens if they miss the mobs, before it could happen anyway.

Can help by sacrificing DPS is not a pro. Having to stop pressing buttons is a con. Having to use band-aid purification instead of forbidden chacra is a con. That's something that nobody wants to do so why list that as a good thing.

Then we get back to the ilevel. How much worse do the problems get when the tank has a weapon 10 or 15 ilevels below best DPS's? 20? Someones going to have to do something that they really don't want to be doing and it's not anyones fault in particular, just getting screwed over by gear.

There's dungeons out there where the difference between minimum entry and maximum allowed is 60 ilevels. At that point dungeon bosses can become pretty frustrating experiences for everyone involved.

There's a whole another can of worms in the minimum item level system itself that still allows people to get their average up without all of their gear being above minimum, such as their weapon. That's something that still needs to be fixed but as you can probably imagine it didn't help the old system any. I'll also just drop this here because I don't know where else to mention it: NQ exists.

For me the con-list is pretty much losing a bit of flavor in aggro that I'm willing to sacrifice to get rid of all the previous cons. The biggest downside is not being able to troll my friends with Shirk anymore. I don't think tanks are great right now but the old aggro is not why.