My problem was that I was standing on a small wooden deck, and not permitted to leave it as this would trample the flowers. I literally could not move any farther back. There was room for about 15 people to stand in 2 rows to watch the officiant and B & G, + Best Man & MOH. After the ceremony moved most of the watchers away, but just did not have much room to play with. I was forced by light and backdrop to shoot in the less wide part of the rectangular deck.
Admittedly, not a common scenario. But it was real, not hypothetical, and demonstrated at least for me a time when the smaller frame size of the focal points was a limiting factor.
And, I can foresee a wildlife situation as stated with similar limits. How does one focus and recompose on a moving wolf or bear, or bird in flight low over water when one wants part of the background in the shot "above" the subject?
Your points about the distortion outside the center of the image frame are well taken. I'll try to practice the alternative focal points suggestion as well.