Keep in mind that I got unhappy about this because some really not-very-loggy classes in collections now touch the slf4j API and demand a working config.
I see two plausible alternatives.
Alternative #1: remove the test scope. This requires non-JCL users to put some relatively fiddly stuff in their POM, but it avoids requiring everyone to pick one and add it. And the result works out-of-the-box. And for some people, jcl is good enough in terms of logging flexibility.
Alternative #2: rethink this.
2a: use java.util logging. Anyone who wants another backend can use the SLF4J technology.
2b: Borrow from CXF. CXF wanted to (a) support I18N and (b) avoid the situation we are in right now. So, they wrote their own simple logging wrapper. By default, it goes to j.u.l, but by putting a file in classpath you tell it to use some other logger.
In short, they built a mini-SLF4J with two big differences: I18N and a working default configuration. Since that code is sitting in a nearby Apache project, we can pretty easily expropriate it.