With a single script with 50 lines of code, I will forever be able to pick it up again, understand it, use it, improve it. Handling will be quick. No installation, just copy the script, run it, done.

Using a project made of thousands of files and dependencies, there is way more maintenance ahead. Handling is slower and more cumbersome. If the project moves in a direction I don't like, maintaining a fork would be too much work.