After the orc fortress the whole cave is too easy. And if you follow dialog, I would say plot wise spider cave more likely come before orc fortress.
Design-wise I think it's fun to try (reload) this battle until you get lucky or you find a tactic that works better.
I can't say here anything that I didn't say already, except you don't need to be lucky for basically the rest of the game, there is only 2 spots that I think you need luck to overcome that part, that is the spider cave (if you go in level 4), and the final of the demo.
Id disagree that design-wise that's fun. At least the lucky part.
The part of a tactic that works better is ok. yet despite all time i invested in this game, I still can't find a solid tactic for this fight at level 4 that have a high chance of success. Something I did for almost every other fight in this game. yet I can't with this one. At least with reasonable not op chars (as you may know, I reroll any a 85+ character).