There have been multiple suggestions for how to organize icons! I believe we have a bug open for at least a few changes to the system, but we're worried about making the process too complex, so we have to do it carefully. In the meantime, if you want to make your icons sort more easily, you can rename the icons so that your most-used icons have keywords that start with 'a' or '01' (I believe numbers sort before letters, not 100% sure though) -- when you click in the box to change an icon's keywords, a checkbox will appear underneath named "Rename keywords", and as long as you check that checkbox when you change the keywords, all previous uses of the icon will change with (rather than renaming a keyword breaking all old uses of the icon).