Most of us have had guild turnover, as guilds become inactive or no longer meet our needs. It would be a huge QoL improvement if I could reorder my guilds. I would be able to keep social, pve, PvP and trade guilds in the same spot (and chat color) even when those actual guilds change.
One of my guilds recently merged with another and disbanded, so we all dropped the guild, which moved all of our guilds up one position, placing the new one in G5. It reminded me how annoying it is to me every time I have turned over. Having to change all my chat colors, and retraining myself to use G2 for my main trade guild, and G3 for the second one, and G5 for my pve guild, which is the same members and events that used to be in G2.
My current "guild merge" scenario is uncommon, but the annoyance of shifting guild positions is real. In talking with other guildies about this, several people said that over the years they've ended up staying in guilds they didn't like any more, just to prevent guild reordering.
Battle not with monsters, lest ye become a monster, and if you gaze into the abyss, the abyss gazes also into you. ~Friedrich Nietzsche