HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

...I don't like it when one thing looks native, and another clearly feels foreign. If there isn't such an obvious difference, then everything is fine.

This is very noticeable in Heroes of Might and Magic. I don't want to say that Heroes of Might and Magic is bad – it's just a different game, for a different audience.
In Heroes of Might and Magic, this is less noticeable, and the gameplay is almost unchanged, and the graphics are supposedly better than the original, but the atmosphere (due to the new graphics) turned out to be somewhat darker – that's all.
I wouldn't say that the New Dawn mod changed the gameplay. Quick battles are not a mandatory element of the game; it's an option (like auto-battle in the original game) that I never used.
But such a feature of the Restoration of Erathia as hiring all heroes with a full starting army, I clearly don't like – defending it, in my opinion, is even greater conservatism than the unwillingness to introduce elements into the game that significantly change the gameplay.