Well, they're dictating that if you want them to use it, do it this way. Some people want others to use the programs they write; for such people, the GP actually has been given the right to have some valid say in the matter.
Why CLIs in particular? Because they usually are smaller tools. For a big, important tool, you might be willing to jump through more hoops (installing the right runtime), but for a smaller, less important tool, it's just not worth it.