This is what I found on the forums:
March 9, 2006
*** User Interface ***
- You can now zoom your third person camera out farther! If you wish to restrict the camera distance, you can do so by setting ics_maxcameradistance in your eq2.ini (old default was 10m, new default is 15m).
So hopefully they won't lower that due to some feedback about possibly raising it.
It also makes me wonder if you could just remove the line from the eq2ui.ini file that sets it to 15 and it will just default at a max of 15? That seems to be what they are suggesting.
As a final note, I did some more testing and have come to the conclusion that 15 is the furthest that it will go as in all of my tests 15 is the same distance as 20.