They did though. They completely rewrote this organism's genome. That's a major technical achievement!

Imagine you're writing a text editor and you get it working well enough to replace spaces with tabs throughout its own source code. Sure, you're not changing the semantic meaning of the code --- but still you're demonstrating that your tool actually works and that it's capable of controlled global edits that don't completely wreck what you're trying to modify. That'd be a pretty major milestone in your text editor project.

This global DNA search-and-replace is the same kind of milestone.