I think the problem is that most of my playtime was during the v0.2, where with the slimes being present for boss fights plus the bosses doing full damage rather than 80%, we all continued to over-prepare for the boss and fear the portals too much.
After playing several games with 2 human players and 2 hard A.I.s, we've had much better results fighting Kourok and the balance feels great now. Sometimes we'll attempt the boss at level 10 or 11 for the slim shot at victory, and it's rare for someone not to try the boss portal at level 14 and higher, which seems about right.
I'm obsessed with getting better at using ranged weapons after seeing that they were buffed in the last patch - it's slow going yet

my aim isn't quite where it needs to be, methinks.
There are two things I think might bear a bit of tinkering, balance-wise, right now:
1. The flying green octopus monster is great, though the A.I. might need a little tweaking in dealing with it. Melee-only AIs never seem to be able to actually hit it - I think perhaps they need to try swining at the octopus as soon as it starts to swoop at them rather than afterward. Vs. human players the flying octopus seems fine.
2. Fetid discharge, in our group, is the new ultimate spell. Even die-hard Advanced Dodge Roll/Hyperdash players like me have come to just stick to fetid discharge. The combination of low cost, fast recharge/long duration, and large area make it a clear winner for our group. It's also super effective against both Kourok and Ghidrak, as well as most monsters. If other users are reporting the same, I think maybe reducing the duration or increasing the ability's recharge time (or simply raising the gold cost to purchase the book) might be a good idea to promote variety.
EDIT: Talking with my play group, we did think of one other comment:
The current potion format for the miscellaneous ability boosing potions (+2 Str, -1 Agi, etc.) is in some ways less appealing to us than the percentage-based system in v0.1. The issue is that, as players, we have no idea what, for example, +2 Str actually means. We know it's raising damage by some amount, but we don't know how much strength we have already or how strength affects our actual damage. Likewise agility and stamina. As a result, we generally just buy every such potion, if we can afford it, without even considering what type it is, because all we know is that +2 / -1 is a net gain. Perhaps some dynamic text could appear next to the potion indicating the percentage increase/decrease over the current values, e.g.: +2 Strength (+13% more damage per hit), -1 Agility (6% decrease in movement speed, 1% decrease in attack speed). This might help make potion purchasing a bit more strategic, as it was in the original system (with potions with very dramatic changes to HP, damage, and speed).