I agree, this is context dependent. If the email clearly touches upon multiple topics and is separated into several questions, it can be better to answer point by point. Still, to me, ripping my message apart and inserting the comments feels a bit off, as if you were my prof or teacher grading and commenting and critiquing my paper.

Of course, answering inplace makes it harder to weasel out of answering some of the points. In that sense it's more honest and straightforward to write it inbetween.

> ultimately no way not to offend people who are dying to be offended

This is absolutely true. One should not assume too much based on small things like this, assume good intentions until clearly proven otherwise instead of reacting to minor "clues" and "signs". But on the other hand when producing text, it's also good to know how they are culturally interpreted around you. You can say all that is a "you problem" but I don't think that thinking leads to a good life.