Is there any reason for rain to do so much structural damage if you don’t have a roof

I like to build in this game. I build pretty big houses, they aren't as good as half of the big builds posted here but I like them. I don't really know what I'm going to build when I start, I tend to figure it out as I go. The roof is the last part and it's typically pretty complicated. If it rains while I am building, all of the wood gets completely fucked and turns green and it takes literally hours to repair it all. If you use even remotely complicated support structures (you don't have to but it kinda looks nice…) then you have to destroy half of your house 1 block at a time just to reach the supports underneath to repair them. I guess you don't have to repair anything that isn't readily visible, but it's still kind of annoying to know that half of your house is fucked.

Am I a noob? Is this a necessary mechanic to have in the game? It's really, really frustrating and it seems pointless to me.