What is your opinion about Heroes IV?

You missed a bunch of other bugs, the caravan feature that ruined the game...

This is a very good thing, and it was implemented in Heroes 5, it makes the game easier. Otherwise, it gets tiresome to buy a hero, take an army from one hero, give it to another, run around in dwellings, but here the system is much simpler, and that's a good thing.

daily increase,...

I agree, weekly is better.

inconsistency with the series (killing off some factions or mixing them)

But there have to be reforms, otherwise you would be playing with only 4 factions, like in Heroes 1.

and the stupid magic system, in which one clearly dominated the others...

It's a normal magic system, it was better than the elemental one, it was distributed among the main actions.
Life - blessings
Death - curses
Order - a mix of all magics
Chaos - damage
Nature - summoning.
And I like this system. And then I think that this argument is eternal, and it needs to be stopped, otherwise the Wanderer will delete everything