Davids is windows.
he specifically is missing the GD library.
I don't know the details of the server -i.e whether it's a shared hosting server, a managed or self managed box.
I've seen hosting plans before where this library is not included in the PHP distribution, and it is included on higher hosting plans from the same host.
php graphic generation is reasonably processor intensive.
given the curent problems with white screens, which IMHO seem like a script time out problem I don't see as it's omething that Davids going to rush into implementing, putting additional load onto the server before he's sorted the white screen problem.
also, I don't know whether David has a test server set up anywhere that would let him test this before implementing it. this would cause additional delay between the suggestion time and the implentation time.
assuming that davd has a managed host he may not even have acces to the PHP.ini file to enable this library.
I know that this library does work on windows as i have it running on my own development server.
I'm sure that this is something that David will look into, though I imagine that this is fairly low priority.