well, it depends on how wide an audience you'd like to reach. no gui means reaching only people who are not only comfortable editing files like that but who don't find that so alien to their workflow that they just don't do it.  gui reaches everyone willing to run a python plug-in in poser, which is far from everyone but still a much larger group.

personally, i'm not so greedy as to ask for a gui, but i'll admit that it would be ultra-appreciated.  just to be be able to browse for the file within the interface instead of going to the explorer, finding the new file, copying the location and changing the slashes to colons would be stupendous.  on the other hand, that seems perfectly easy and clear to edit, imho. but i'm not afraid of code.