Q:

I feel that moderator removed interesting part of question while editing - would it be ethical to undo his edit?

To be more specific:
https://rpg.stackexchange.com/posts/78349/revisions
I'm talking about change №3 by mzyzplk -
"When did that happen" - this line was removed by moderator - but actually, I feel that this was an interesting, and quite organic part of the question - it forms context and adds life to it. I never played 5e, but sometimes become interested about some minor design features. Also, it is interesting to know WHEN was the followers feature dropped from DnD as part of character development. So - at least for me - that removed question feels relevant. 
But is it ethical to redo edits of other moderators? Or better way would be starting new question?

A:

I do think this should be asked separately, and it was good to remove.
There's two questions there: one's a very immediate, useful-right-now mechanical question answerable by anyone with D&D 5e expertise. The other's a more curiosity-oriented question that doesn't have the same useful-right-now impact, and requires an entirely different set of expertise (understanding fighters through the editions).
Those two questions hold each other back being asked together, because people who don't know or aren't confident on one will hold off on the other. Also, for the sake of the history question, it's probably better off we find out what did happen before asking when it happened. (Did they really lose the ability to get followers? Did it get moved instead? Don't know.)

To the matter of whether it's ethical to undo edits of other moderators: yes, sure, they're humans like the rest of us and aren't perfect at editing. Just be careful of two things: (a) make sure they weren't trying to end an edit war, (b) make sure you're definitely improving the question and, if you're rolling back an edit, make sure it definitely wasn't improving things (but this applies to any kind of editing, even not involving moderators).
If you're not sure, you can totally ask on meta (like you did here, good question!) or ping them in comments expressing your uncertainty about some part of their edit.

A:

Like @dopplegreener said, those are two separate questions and since that part of the question was basically represented with four words, I cut them to keep answers focused on your core problem.  If you really want a history-of-gaming question about it you can ask it.  Hint, the answer is "they stopped giving followers automatically as a class feature in later editions of D&D."

