I tried my first ritual on a ‘new’ main I am enjoying (Devourer DH, is just surprisingly really fun for me). And it was actually fun to play through it. I’m actually interested in seeing what the renown adds, challenges, and to raise my ilvl to take on the higher difficulties (tiers).
Just thought I’d put out some positivity. 
I don’t see why they weren’t folded into delves 
Why make another “new” thing instead of expanding on the delves a bit more?
Well they are doing more new delves soon. This content functions differently on a tech level. It lets them kind of deviate and experiment and see what works etc…
I like that they utilized the existing zone. Delves are getting plenty this year so I appreciate the variety with Rituals. 
I tried rituals today too. It was okay. Kind of like a sped up and condensed key. Not a fan of delves because I’ve never enjoyed quests or content that you do with npc’s.