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

In HD, I won't be making changes for every little thing, for every minor adjustment to an option, as some would like.

Changing the quick battle mechanic after introducing the ability to replay it is no longer a minor thing.

First, it's technically more complex, more labor-intensive, and time-consuming.

This is an argument. There are 3 options here:
1. Don't introduce the most controversial fixes.
2. Spend time and introduce them as optional.
3. Introduce them rigidly and hope that the gaming community will come to its senses and start playing with them. At the same time, it is obvious that the hope is all the less, the more controversial the changes are.

Secondly, I don't understand the point of choosing: play SoD with X or Y percent of fixes. If it's going to be bug-free, then it should be bug-free; otherwise - with the original bugs.

At the very least, there is a problem with a comprehensive and universally accepted list of bugs that need to be fixed. For some, the sulfur in the nagabank is a bug, and for others, the damage from towers.
In my opinion, it's not worth lumping everything together; there are features, bugs, BUGS, BUGS, etc.

And I don't understand the indignation about the fact that in order to play with some features with an opponent, you need to negotiate.

The indignation (an unfortunate word, rather, disappointment) is caused not by the fact that it is necessary to negotiate, there is nothing to be done about it, but by the introduction of changes that make a positive outcome of the negotiations extremely unlikely.

No one is surprised that in order to play with Conflict, collections, and other additions and fixes, you need to persuade your opponent to play SoD, and not RoE, or if you want to play with the features of WoG, you need to persuade them to play WoG, and not SoD.

It's a bit of an exaggeration; no one plays RoE online. With WoG, yes, there is a problem.

However, SoD cannot play with RoE according to the rules of RoE, and WoG cannot play with SoD according to the rules of SoD. But HD+ can play with SoD according to the rules of SoD - and this is a big, in my opinion, convenience.

There is no arguing with that. It seems that this is what it is leading to: you will have to use only this convenience of the mod.