If I understand correctly then your point is - if changes are made to one thing, why shouldn't changes be made to the other? Well the reason is because each thing needs to be treated individually.
When you're talking about extra anims in fatalities, I'm not sure whether you're talking about the amount of sprites or new movements entirely. If it's the latter, I wouldn't want to see that either. Just the amount of sprites that are required in HD to make the original movements believable, and if there's something about the original that conflicts with that, only then should it be updated/changed. A zoom effect is not something that was in any of the classics, and so it doesn't belong in this HD upgrade - it's important to remember that it is just an upgrade, not a re-imagining.
About the characters, I don't think the comics should be a reference. For this to resemble the original MK1 as much as possible, the HD sprites should be entirely based on the original sprites and photos of the actors. The comics were a separate thing, and even if you prefer the costume designs in them, they weren't made for the game and so aren't the correct reference.
As for Goro, I was under the impression that he was being based mostly on the in-game
version. It certainly looks like it at least. But since obviously it was not an actor in costume, I think that along with the clay model and its sprites, the original artist sketch of how he was intended to look could also be a valid reference. There is a convincing similarity between the sketch and the model too.
Although, I'm not so militant that I am totally against adding any small, extra details to the HD sprites that weren't in the original. After all, MK1 was so low-res, that so much more detail is expected in this HD version. If there are other details in the original sketches for the characters, and could be incorporated while still preserving the MK1 look, then with good judgement it could work. But it should not deviate from the original sprites in an obvious way. That's my take on it.
I can see why you would think the example of KI & SF3 would be relevant. However you are missing one crucial element - like I said, those games are old, they are low resolution and made for outdated TVs. They also have an illustrated style. For a realistic portrayal of characters, modern tech requires higher resolutions which require higher amounts of sprites to look natural. So both those examples are irrelevant IMO - this MK is in HD and is meant to represent digitized actors to the best of its ability, within the means of 3D modeling. If you are trying to convincingly portray real people, then both the graphics and the movement are just as important.
The original MK was able to get away with a lot because of the tech at the time it was made, and the fact that it had never been done before gave it even more impact. Just as the quality of it would've been compared to others in its time, the quality of this remake will be compared to other games today. It's conditioning.
Anyway that's probably the best way I can explain why the animations should look as natural as they can within the limitations we have. Which simply means we need a lot of sprites.