I guess the same could be said for the penalty arc, there is no guarantee that it will be used at all in a game.
My thinking is that at both the kick off and a penalty kick there are numerous players around the vicinity so by having markings it makes it easier for a referee to see encroachment (or ignore it, before nemesis replies
) At a corner there are usually only one or two players so easier to manage.
Also on a small pitch (minimum 50 yds), with a 44 yd wide penalty area, then if you had 10 yard corner arcs these would go into the penalty area and cause a mess of lines.
Of course the centre circle’s only official use is how you describe, but as referee’s know it can really help with estimation of 10 yds for set free kicks within the rest of the field. As part of my pre-match I always walk out the edge of the centre circle to the edge of the penalty arc and touchline to edge of penalty area as that then gives me an idea of the dimensions of the field of play and a rough idea of having players back 10 yards in non ceremonial free kicks.
* I’ve used yards as that’s how I was taught, youngsters can convert to metres