"A script's just a stage to getting to the finished article. Once the thing's been published, what's the point of the script?"
For the person who wrote it, there's not much point in keeping the script - as you say, it's a part of a process that results in the finished article.
However, to the budding writer or artist, a script can be a useful insight into how the process works. True, you're going to find out a lot of this stuff yourself by trial and error, but being able to look at how the guys who do this for a living go about it is always interesting, and often instructive.