The problem with Gradle is that people try to use it, and so try to understand it, and then treat the sunk cost to understand it as a reason to keep using it. Bruce correctly sees being locked into Gradle as a way to need his expertise, but that is not a reason to follow him down the rabbit hole.
The correct response to discovering the nature of Gradle is to abandon it, immediately. (Similarly Waf, and Scons.) The world does not need yet another one-or-two-language-target build system, or another build system as full general scripting language. Things work better when you don't need expertise. A build system should be just barely powerful enough to do builds, but not powerful enough to mystify. A build system should work equally well for all the languages you might find you need to use. A build system should not need to be studied to be understood: isolated examples should suffice for each need.
Similarly, the build for a project should not need to be understood: everything you need to know about what you are looking at should be right there, or (failing that) in a single, central place for the project. The build should be the least interesting or engaging part of the project; the project itself inevitably demands more attention than you can spare. A build system that demands attention is a child screaming when you need to work.
The correct response to discovering the nature of Gradle is to abandon it, immediately. (Similarly Waf, and Scons.) The world does not need yet another one-or-two-language-target build system, or another build system as full general scripting language. Things work better when you don't need expertise. A build system should be just barely powerful enough to do builds, but not powerful enough to mystify. A build system should work equally well for all the languages you might find you need to use. A build system should not need to be studied to be understood: isolated examples should suffice for each need.
Similarly, the build for a project should not need to be understood: everything you need to know about what you are looking at should be right there, or (failing that) in a single, central place for the project. The build should be the least interesting or engaging part of the project; the project itself inevitably demands more attention than you can spare. A build system that demands attention is a child screaming when you need to work.