Actually it is an issue because there is only context once per topic. Replies don’t always happen to the last message in a topic. So when notifications come, for example Adding custom fields with custom controls to the user page which is an out-of-sequence reply to my message (not the last one), I get no context in the email notification what the author is replying to.
If I look up in the previous messages (including the deleted ones!) in the thread in my email inbox, I can only assume he’s replying to the previous post. In that case, it makes no sense at all. And, since I don’t have an email notification of my own reply (which the author was actually replying to, and which I would if I had sent an email by virtue of a mail client keeping replies together in the thread) it makes things even more confusing. 