I think you'll find it tough to get permission even for a step climb in busy airspace.
Looking at it in the way figair puts it then it depends with what you are comparing the step climb. If you are comparing it with trucking along level for the trip, then the purpose is to reduce fuel consumption (which does increase range as a side issue. Don't you hate JAA?). If comparing with a cruise climb then it assists ATC, and may aid adherence to ATC procedures. Then again in reality ATC may tell you to descend for traffic flow, so the answer is inelegant.
The point is the best answer I can see at the moment (note I have only taught P of F, not performance) is to increase range. Depending on how the question is worded, ATC compliance is a possibility, but I would have to see more precise feedback.