The inherent beauty of the tools responsive design gives us is the freedom to plan for an uncertain future.
Can’t see an immediate “requirement” for a client site to be responsive? Still saying “it depends“? Why not consider responsive design as a tool for the future – the one where none of us know what’s going to happen?
Restrictions in building fixed dimension sites aren’t going to bite you in the backside right now but ultimately they will. It may be in 6 months, it may be in 2 years but if you start at least experimenting with making your sites flow and change you’re going to be more marketable in a year than if you don’t.