Vraiment, vous avez raison, monsieur Sharkû
There is no such a need, indeed. I was beeing overly severe in this respect. Let me modify my demand

:
If the edit you are going to make is prior to posted answers to your original post, go ahead without explanations. Per instance:
24-01-05 6:00 PM Original Post
24-01-05 6:30 PM Edit
24-01-05 7:00 PM Post #2
No reason required - it is obvious that post #2 addresses the issues raised by Original Post and Edit together
On the other hand:
24-01-05 6:00 PM Original Post
24-01-05 8:00 PM Edit
24-01-05 7:00 PM Post #2
In that case, it is better to give reason.
cheers