Sometimes (see my comment upthread), it can't really be helped. I had the same reaction to the Service manual when a headlight on my 350Z went out: what do you mean I have to remove the bumper to change a lightbulb? Makes no sense.

However, while it's possible to do it without removing the bumper (I go in through the wheel well), it's harder that way. The reality is that there isn't a lot of room in the first place, and headlights can last a very long time, so for an infrequent service it does make sense.