Because Maven doesn't require a background daemon eating 2GB of memory to be fast and IDEs can actually provide code completion and documentation while typing.
Android is the only reason to have to put up with Gradle.
Gradle 5 lets you write the build scripts in Kotlin, which is supposed to address the code completion issue. (And the continuous build mode is a nice feature!)
2GB for a cache that isn't required by alternatives for the same result just feels bad.
And don't get me started into turning build scripts into full blown applications impossible to decipher what is going on without some kind of debugging process.
