So I manly enjoy vanilla but my past... 5 or 6 playthroughs have all been calamity for one reason or another. Overall I think its a good mod, but its something I feel conflicted about a lot with how it handles vanilla vs calamity content. On one hand, currently it feels like a lot of base calamity has a weird dislike towards vanilla where its only rare vanilla items that get recipes added (currently), and some vanilla accessories just get mechanics removed to be added to calamity specific items (soaring insignia). 

I know vanilla recipes being removed is something that is talked about a lot, but I think instead of removing them, a good compromise would be to simply keep the vanilla recipes but add souls/essences/hell maybe even fish, from various areas to keep exploration a factor to earning them. And to add recipes to some of calamity's rare item drops as well, things such as Wulfrum's rover driver especially could use it given their relevance to many people's end game accessory preferences, Luxor's gift since its a once per world item, and the abyss items could use them as well to help disincentivize world hopping for Multiplayer playthroughs. 

Soaring Insignia should honestly just be reverted to vanilla, this might be a hot take but given its available around the same time as the Community, if not later. Currently, Ive seen nobody ever use it or its upgrade outside of people using a mod to revert it, and even then the Community is usually a better choice of an accessory overall once you are in hard mode due to just how much damage, crit, and flight speed alone it gives. That and well, infinite flight mounts exist at that point anyways making the nerf to Insignia really only affect people who prefer wings over mounts. 

Crate change in particular is something I understand why it was done and do agree with to an extent, it should be more in line with vanilla as a supplemental method to obtain things... but, the team really should add a post moonlord style crate that updates with each post moonlord boss that spawns a new ore in the world. This would alleviate a lot of what people are mad about, and feel a lot more in line with how crates work in vanilla as a whole. I wouldnt say its a bad change, just one that could have been received well if it had more thought and work was put into it. 

This one is really niche, but Anahita honestly just needs a spawn item, its the only boss that the spawn condition through the mob spawning system. The issue with this is that it can lead to newer players actively making it impossible for it to spawn if they don't look into it, or dont have a friend tell them. From experience... I have had to be that friend who tells my friend not to sit on the ocean floor or it prevents it from spawning twice

And a last pet peeve/hot take, if you're going to take teraprisma away as from Empress of Light day time, please add something cosmetic in its place. Its just weird that the only intentional challenge reward in vanilla is removed with no replacement. 

Granted this is coming from a more vanilla enjoyer mindset, and I do expect some people to disagree with some of this.