thats boring and inconsistent. no other biome gets flat immunity, they're instead preserved by mixing. jungle grass becomes corrupt jungle grass. mud becomes ebonslime or somesuch. its preserved and still allows fighting corruption to be a thing. we even get hallowed *palm trees* and they're just cosmetic, so why not jungle? just make it behave like tainted ice biome does.
a bandaid so it wouldn't be lost entirely. a holdover from before the jungle was significant, just like corruption destroying it was. ice was immune at first too. mud used to be unstable and occasionally collapse on your heads like sand, doesn't do that anymore. ect
its equally protected by being corruptible as by immunity. the only reason it isn't now is it gets destroyed for some odd reason.
Your primary point with regards to this was about Chloro, Shroomite, and Plantera Bulbs, all of which also only appear underground.
what about new players? they're just screwed if it gets eaten before they hit that point because corruption spawned in the middle and they didn't immediately fly over to dig hellevators around it before entering hardmode?
...but you quoted every one of em
if they could be infected green solution would fix that
I have no idea what kind of worlds you spawn in, but I've had some very nasty Small worlds - including one with a corrupt chasm almost exactly in the middle of my jungle - and I've still been able to collect a reasonable amount of chloro from the bottom. While I do agree that jungle infection is very irritating, the chloro fix is a lot more effective, in my opinion, than most people are giving it credit for. Use Green solution to turn the underground Dark Biome into Forest, then use chloro to turn it back into Jungle.
Center purity isn't in any real danger until Hardmode, when you're well equipped to protect your spawn with any number of tools. Additionally, and correct me if I'm wrong, once you're in hardmode, there is no practical purpose in having purity (As opposed to Hallowed for your NPCs).
because currently corruption destroys it and turns it into dirt. if it didn't do that...
I don't really see how Chlorophyte has a meaningful effect... Crimson, Corruption (and even Hallow) can spread through stone. Chlorophyte can't. It's only going to work along exposed surfaces where plants can grow.
To clarify for others: Spraying mud with green solution will turn it into Jungle. (You can reverse Mushroom biomes that way.) Spraying dirt with green solution will turn it into Forest. Since Corruption/Crimson changes the mud into dirt before spreading, it really does destroy the Jungle.
Last time I checked, the Jungle has very little stone in its underground. Chloro isn't going to help you spread the Jungle past its initial borders, but it will slow down encroaching Corruption and Crimson.
That's true. But it was still sufficient to allow Hallow to cover about 50% of Jungle in one of my worlds. (Jungle + Hallow = Awesome
.) Some well-placed Mushrooms + the Lihzahrd Temple on world generation was all that stopped it continuing through. (Only a tiny part of this Hallow spread was due to entering Hardmode.)
That's why it needs it's own stone to replace mud in it's underground area.