If you can't easily reason about dependencies, then your builds will just get more and more bloated.

People who care about build systems are a special kind of nerd. Programmers are often blissfully ignorant of what it takes to build large projects - their experience is based around building toy projects, which is so easy it doesn't really matter what you do.

In my experience, once a project has reached a certain size, you need to lay down simple rules that programmers can understand and follow, to help them from exploding the build times. Modules make that extra hard.