There are, quite literally, an infinite amount of things within SE's means to add to the game, but only a small portion of that infinity can actually be included. There are a lot of reasons for this; workload, design choices, time constraints. Sometimes, even things that the developers would really like to see included can't be or are delayed longer than they would like.
This is true of everything in life. Have you ever wanted to buy something, but thought "I shouldn't, my money would be better spent on something else"? It was in your means, but you thought of a better use for those means. A developer might think "Having a Carbuncle skin usable for Summoner Egi would be so cool, but we shouldn't right now because we've got way too much to do with the upcoming patch and expansion. We should keep our resources focused on that."
An understanding adult is familiar with this sort of thing and doesn't expect every wish of theirs to be practical all the time.