There was some discussion about this back when they added the <macro> command just over a year ago. Unfortunately, having trouble searching for posts that old--search seems to want to cut off arbitrarily before a certain time frame or something, and Google returns a bunch of crap when I try. However, I did find this:

http://forum.square-enix.com/ffxi/th...l=1#post227224
Originally Posted by Hiromichi_Tanaka

We’ve implemented the new macro palette onto the dev. server!



You can now enter up to 8 characters into the macro title box. We were unable to increase the max number of characters you can input in the macro editing menu. However, the title you input will be fully displayed now. If you are using a 1024x resolution or higher with the Windows version or using the HD mode for Xbox 360, these changes to the macro palette will be automatically switch over. If you are using a lower resolution, SD mode, or a PlayStation 2, the size of the macro palette will remain the original size. We weren’t able to launch this onto the Test Server this week, but we will be implementing it sometime next week. I hope you’re all looking forward to it!

Oh…did you notice the chat widget?
The developers have secretly been working on a new chat widget for Windows and Xbox 360 that will allow you to adjust the number of lines and width of the box. This will also be implemented onto the test server next week, so please try it out!
Note the sentence that I bolded in the quote. This implies that there is in fact an issue in coding or other resources that make expansion of the macro entry system difficult. I'm wanting to say there was some mention of a concern over the console GUI design--may have been a reference to a real estate issue on the PS2, not sure. But there was something brought up about issues with expanding macros for the PS2. Which, as we all know, they have traditionally been reluctant to make major changes to the interface that cannot also be done on the PS2, in the interest of keeping the player experience balanced.