Like, randomized combat is a good thing in small doses. Unpredictability is fun and it can test the player's ability to react to unexpected situations. But when you've got a significant chance to fail casting your spell [...]
I totally agree.
In the latest version of Infra Arcana, I erased a lot of senseless randomization for the reasons you mention. In particular, it used to be that spells had a certain percent chance of success (I tried slightly different approaches to this in many versions) - and damn it was frustrating to use! Now it always works, but drains spirit (mana), feels much more satisfying and tactically interesting.
Another similar issue was the resistance system - there were resistance vs physical effects and resistance vs mental effects, measured in percent. Various traits gave bonuses to these. When something tried to blind you for example, there was a check against your physical resistance - if it was 40%, you had a 40% chance to avoid the effect. It just felt... really random, in bad and confusing way. Even if you had very high resistance (like 80%), you could still be afflicted many times in a row, making you wonder if those traits really did any good at all.
Something like a
shuffle bag could possibly have solved it to some degree. But I chose to rip out the system and change it to something deterministic. This feels more fun to me. If something blinds you, then you're blind - unless you are resistant to blindness, then you're guaranteed to be immune
1. It's certainly more tactical and challenging than just rolling the dice and hoping for the best.
1IIRC Nethack uses this system, and have often been criticized for it - but mostly because (some) resistances are too easy to attain.