Unfortunately, Gradle chose Groovy for its programming interface, and Groovy was designed to be complex so its backers could sell conferences, courses, and consultants. Thankfully, it looks like Gradle's going polyglot soon, their Gradle 2 roadmap [1] talks about a configuration-on-demand build model which could expose an API usable by any scripting language, like with vertX.
[1] http://forums.gradle.org/gradle/topics/revolutionary_new_gra...