Being able to programmatically create URLs to load things would make the web loading tools much more flexible.
IE: Im trying to load data from a google calendar that requires a querystring with the start date, and being able to supply that calculated on the fly makes things much easier.
It would also allow the string loader to provide URLs for the image loader so we could change what images we have loading without having to replace the image that is being hosted or reupload the world with a new URL.