What were your expectations for Heroes 4?

Again, just my opinion. I don't claim to be right and I respect yours, Alex Ghost. This is how I see it... the innovations of the 4th installment:

Actually, I didn't expect the heroes to be so replayable - as ordinary units - in a way, this is wrong - because heroes are the primary targets for enemy archers... and they die quickly.

This is both the essence and the highlight at the same time. The hero is a participant in the battle, a participant in the events. He doesn't stand aside and do nothing. He is responsible for his army and for himself. It won't be easy to take down a hero who is well-equipped. In the early game, use the "Immortality" potion. The army, in turn, doesn't stand still and constantly distracts attention from the hero.

Furthermore, even after a victory, it looks strange - the creatures wander around with the coffin of their leader - in reality, of course, they would, but not for so long - and they also rush into battle against the enemies.

Well, they don't wander around... why would they wander? Let them go to the Castle, there should always be a hero there. If not, hire a new one. You can't do without a hero. There's no point in fighting monsters.

Furthermore, it's a pity that the developers didn't come up with a system for arranging troops, like in the 5th installment - this would help against archers - you could place slow units to protect the hero from arrows, and fast units closer to the enemy's front lines.

Well, it's already similar. You can also place the hero on the rear flank, covering him with someone from the front. Archers are generally better kept in the rear. They will even just get in the way of other warrior units...

Another questionable aspect is the minotaur's ability to completely reflect attacks with some probability - it's interesting, but to reflect the attack of a stronger creature - in particular, the Black Dragon's breath - is nonsense or a bug.

Honestly... my minotaur has never reflected the Black Dragon's breath. Maybe because I don't remember playing Chaos against Chaos :D