I work at an Informatica shop, which will be morphing into an Ab Initio shop soon; so the RCS question isn't so much "We don't need" but "What can we use?".
Ab Initio purportedly has an integrated version control system, that interfaces with their Metadata Repository, forcing capture of the process metadata at check-in.
Informatica, on the other hand, has a version tracking system that assigns a new version number to a process upon saving a change, *if* the developer chooses (which *never* happens). So, for changes that are moving into production, we copy off an XML version of the process being replaced by a newer version.