Why should I? (or changing from usable to unusable)

The title Build scripts with Groovy and Ant lead me to a nice thinking process before I start reading it. I thought that Groovy was integrated with Ant the way javascript through Rhino is integrated, the way Python is integrated, so on. But no, the article suggests that I can move my Ant to a Groovy source. For me this sounds even worse than moving from Ant to Makefiles (if I were Hani I should say instead moving from Ant to Maven? [blink/]) or moving from maintainable to unmaintainable. I find myself wondering why should I do this? Update: the story continues. Filip took the time to answer and obviously I continued. I wonder if we can build something out of it? What do you think?