I'll defend the rain a little bit, mostly as devil's advocate:
Climbing is super overpowered without rain--you can avoid any open world combat encounter by climbing around it. It's the #1 solution to any problem. The prime example is the winding path that leads to Zora's Domain, it's meant to be a long combat gauntlet, but with climbing, there's zero reason to experience any of it, climbing past is purely better. So they added perma-rain there.
It's meant to be a game about changing your mind and getting distracted. You were heading toward something, but now it's raining, so you look around, and say "hey what's this big rock over here" and you check it out. A new adventure interrupts your current adventure!
Rain means that often, a straight line is definitely NOT the best path from A to B. This makes you care about the world and its terrain more, forcing you to adapt. It's like how in World of Warcraft, as soon as you unlock flying, the game feels a lot less immersive. So the devs always hold back flying for the first ~year of any expansion.
You can still climb in the rain, if you try hard enough. You start to get a feel for when the Slipping occurs, and if you do a Dash Upward right before the Slip, you don't lose any progress, and now you can do ~3 more seconds of climbing before the next Slip.
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