We can't provide a definitive answer because it was the question owner that rolled back the changes. I can say that your edits were good -- please continue to make improvements like this to questions you see that need it!
Some people do not like the idea of other people editing their text, regardless of the changes made. Perhaps that was the motivation here as well, but that is speculation. If that's the case, hopefully as they participate more, they will get used to how things work here and will appreciate the dedication to clarity and quality the editing process enables.
At any rate, do not worry too much about it. If you think a rollback is particularly problematic, go ahead and flag it for moderator attention. We will look into it. Sometimes it isn't worth losing sleep over and it's best to just move on.