Well, if someone else had bought it instead of Ubisoft, it might have been even worse! But I'm certain (IMHO - 100%) that 3DO and NWC would have done a better job!!!
And it's unfair to criticize 3DO and NWC for the 4th installment, because they've already done a lot, and there's simply no room for more. You're judging (excuse my expression) inhumanely and unrealistically. For example, the interface is much better than in the 5th game, and I don't think anyone can argue with that! If you say that the 4th game is the least popular in the series, I agree. But if you say that it's complete garbage, then you have a very limited range of games you've tried. Because there are truly "terrible" games, and the 4th game doesn't belong to them.
I read somewhere (though I don't know if it's true) that when creating the 4th game, they took into account the opinions of fans and considered their ideas and suggestions. If this is true, then that's the reason.
Because it's obvious that the game was made with a focus on maximum convenience and innovation (apparently, they didn't just want to make the same game with new graphics, although they probably wouldn't have gone bankrupt that way). But something went wrong, and it turned out to be a mess. But try to say what's "wrong" with it and verbally improve the game, and you'll probably just end up going back to Heroes 3 in parts. And try to change the game a lot, adding a lot of new and cool things, and the game will again be cluttered with junk, even if everything looks great at first glance (because when they first told me about the innovations in the 4th game, I liked everything). And the conclusion is this: you can't do better, and you shouldn't try!!!! (And having learned this, they would have made a great game, but it didn't happen, and Ubisoft and Nival have already drawn this conclusion (sadly:( ))