Not being able to discard cards is a bug. Arachas Drones are -well- there are bugs too. However, the weather is just a 1 + 1 kind of mechanic. The weather ticks on the opponent's turn and Drones spawn on the opponent's turn when units are killed. I don't think this is really an issue. If you want to talk about weather, I find it more odd that Fog can kill Foglets and Frost can kill Wild Hunt units. But even that isn't an issue, gameplay-wise.
I think lore-wise a lot more thought could go into the game, 100% agree with you. There should be units immune to some effects, rather than having units that are 'just' immune, or affected as you say by the wrong stuff.
But we're talking about a weather effect but if you HAPPEN to draw Arachas, all your weather cards - which aren't exactly great to begin with, I still have NO idea why CDPR put a time limit on the effect - are rendered more or less useless, purely because the weather only takes effect on the opponents turn.
Any damage caused by any card you play should be done on YOUR turn. No way should you kill a drone and it just pops up again!
