as it seems to be a hot subject, my additionnal 2cents:
pd is a graphical language, so a nice gui isn't a luxury. it provide good readability, which improve the developpement time and even more the maintenance time.
to have a good readability allow you to understand what you have done when you come back way later, allows other people to understand your work.
in textual language readability is known to be important for years. some textual language have a poor readibility and are qualified of 'write only' language.
is it possible to improve puredata gui ? well look at max/MSP one, i think they did a better job. not mandatorily the one we want to copy but a better one according to me.