This is actually a bug and was not intentional!
I didn’t have time to get it in for this patch, but it is fixed in the next one. Sorry about that!
As to your question about specific details, here is some info:
We have work to do on both the strategic layer and the tactical layer. In a game like Heroes, these two things are very connected as well, which complicates things, as you might imagine.
Strategy wise, your example of defending the core (and assaulting an enemy core) properly is high on our priority list, along with some other danger assessment issues.
There is some more work to do on the tactical front (teamfighting and micro assessment). Our agents use their abilities pretty well when they are actually committed to a fight or objective, but they currently don’t do so as reliably as we would like.
Additionally, there is some work to be done to fix issues with incorrect execution of some objective related actions like taking Blackheart’s chest and turning in coins.
They do! AI at lower difficulties are worse ad doing individual combos and worse as a team at chaining their abilities together. They also have worse aim and are worse at noticing hidden and stealthed heroes.
However, we wanted to maintain the integrity of the experience regardless of the difficulty, so we don’t outright disable abilities that might be hard to play against.