Spiders should be difficult. After you get armor and tier 2 weapons they become very manageable, especially orb weavers. Spiders are high risk high reward. One of the best parts about this game was the fear of being hunted by a spider in the early game. Once you have progressed far enough though there isn't that same fear you just beat the spider to death with the tier 3 mallet and its very underwhelming. I really think nerfing spiders would make this game boring. There is no other creature currently in the game that is even remotely a challenge.