>>6278759
You are right that .333 to .375 is a tiny percent increase, but it's a die in a dice pool. This compounds to a much larger chance of success the larger the die pool becomes.
Let's say for an 8 die roll, you got three successes or more instead. On a d6, the odds of this are 53.1%. On D8s with these rules, the odds become 63%. Without the rule that the number required for success rises, i.e. half the numbers on the d8 are now the range of success, the odds for rolling three or more successes would increase to 85.5% - nearly trivial rates. The odds of rolling 5 successes on 9 rolls, like your Brave engagement, have risen from 14.4% to 21.6% because of your step up to d8, whereas your suggestion that 5 is included as success would put the odds of that at a neat 50% chance. 5/9 successes would happen literally half the time. Given this is something you can just apply before a mission, you can be awarded circumstantial advantage dice bonuses via flanking or whathaveyou, and with a larger number of noita you can apply this to the every person rolling dice in the vicinity, this precaution was warranted. In Solarpunk #6 I specified that d8s use 6-7-8 for success the moment it was introduced into play. I'm sorry if I hadn't said that out loud this thread.
If you have further questions, punch funny numbers into here. Divide the fraction of a die's faces you want to consider as a success, punch in the number of dice in the pool, and how many succeed to get the chances of that roll or better happening.
https://stattrek.com/online-calculator/binomial