The one thing I've always wanted for my macros is the ability to change the color of individual buttons, pallettes, and sets of macros. All of my jobs have lines and lines of macros, and if I could give each line a distinctive color, I'd be much less likely to accidentally start singing fire carol when I wanted to sing horde lullaby. I don't think icons would help me out as much as customizable colors would, though to be fair it's been like half a year since I checked out ff14, so I forget how immediately recognizable the icon system is.