Please implement automatic generation of recommends in rpmbuild. I can provide a patch if needed.
RPM 4.12 alpha supports manual recommends specification it spec files, but doesn't support recommends generation via file classifiers (rpmfc). I believe that this feature is necessary in order to fully utilise the power of soft dependencies.
In Java and dynamic languages automatic dependency generation plays an important role. Java SIG would like  to use this feature to for generating optional pagckage dependencies.
Version-Release number of selected component (if applicable):
This has been implemented upstream already but its unclear at this point whether/when that work will be pulled into 4.12.x.
Fixed in rpm >= 4.12.0-0.beta1.1.fc21.1