seem to recall SE touching on this a long time ago in one of the many DEV Q/A sessions and it was an issue with real estate in the GUI. PS2 has a lower resolution cap, and they can only fit so much info in there or something without a MAJOR overhaul to it.
It may be more easily done for PC and 360 simply because there are more columns/rows to work with at the higher resolution, but then there is the potential additional cost of maintaining the different GUI's with each update. At this stage of the game, SE simply is likely not willing to throw such resources into a game this old.
As for the font thing, changing a system-wide font is not as big an issue as it may seem. Once you determine which font you wish to use, et's basically just a handful of libraries for each font...change a few files and all the text based off those files are changed in one shot. Worst case scenario, you install the new font alongside the original under a differnt name and have to go thorugh and change the pointers in the panels so it loads the new font. The latter is like updating the look/feel of a web app--change the default font referenced in the CSS on one line, and every bit of text on that page using the default font gets changed in one shot. Then you have to find any remaining custom font references and change them to a similar font to match it--usually this also has a similar placeholder so you just change a few more reference fields and it's done.
tldr: seem to recall SE looked into updating the GUI once, but it is too impractical on the PS2 and not worth the resources to do it for 2/3 the platforms supported while having to maintain it differently for just one platform.