It would be great if we could have more ranks in guilds, especially for those guilds that aren't "top end". We have a large selection of GP among our members, not to mention collections, etc. It would be a massive help if we could post orders such as "all member of this rank, attack here; all members of this other rank, attack there" or "all members of this rank, attack; other ranks hold back", etc.
Yes, we could set up the system ourselves within the guild but then we would have to keep explaining it every time we got a new member. It would be much easier if it was game wide and then everyone would know about it regardless of how often the might change guilds.