LOL, no we're being sensible professional designers. Over design is a noob designer trap. More complex means more bugs, harder to implement, and harder for players to understand. The magic under the hood is of no concern, just know that it might rain and thats good enough.
Sometimes grinding down details is the right call. Too many moving parts makes the game harder to balance, and players are wondering why they are freezing but there's 10000 variables at play. It was overdesigned in pre 17 and broken in 17. We'll land on something more simple that works and doesn't break immersion.
heh, I just hope you don't forget to also add in a 'check' to the system that forces it to stop raining after 'X' amount of time, along with having a 'check' that makes it rain after 'X' amount of time.
One of the downfalls of the old system was, rain (along with the constant fog that came with it) got stuck every so often and just stayed, till you exited the game and restarted it (or you loaded the game onto a server, and ran it that way).
The old weather system wasn't terrible, it just needed to have a global effect system as well, instead of being fully biome driven.. well imo.
If it rained in the forest, it needed to rain/snow in the other biomes at varying levels.
Another area that needed adjusting (for me at least):
Was/Is how you are using the different spectrum filters for every biome, which was the cause of the flickering when you had dithering between them.
The dithering was -> immersive <- because then you didn't feel like you just crossed over an invisible barrier and got transported into a new area. Instead the dithering allowed you to ease into the new biome.
Solution:
Use the different spectrum filters like you use the blood moon spectrum (which gets applied globally), and use the different spectrum(s) every couple/few days. Use them globally instead of just per biome, and keep the dithering between biomes.