While for the end-user, the "less-is-more" theory tends to be a huge win, you've got to get into the client's shoes to get where this opposition comes from.
The short answer is: they want to 'get what they're paying for.'
I usually find myself in the sometimes awkward space mediating between board members, designers and the rest of the development team (being a developer myself.)
One thing I notice fairly consistently, especially from complaining devs -no matter how many outlines, specs, project plans, etc… have been seen and agreed on already- business folks often won't support features until they have a design element attached to them.
This is a different kind of problem for the dev team, some important features have no visual, but I think it underlines some important aspects of the common setup.
- Want to assign tasks and see visual indicators of progress
- Usually aren't educated in UX Design
- Usually aren't educated in requirements specs
- Often feel their 'gut reaction' at first glance is close to what an end-user feels.
- See blank space in a similar way to how they see weeks of programming without visual change. In short, it can seem like nothing is getting done.
- Don't fully realize the detail, planning and process as deeply.
Now of course, not all clients are representative of these points; but they're somewhat fair from the usual point-of-view of management. Its a real treat to work with folks who have the experience to let work get done =]
To attempt at offering some solutions:
- Too often, though it may not be admitted, a well considered and placed HD backdrop fixes everything.
- Demonstrate the flow of the experience over multiple situations. Demonstration is key to clients catching on that "there's really something to this"
- Try to educate the client with a strong overview of the rationale being used.
- Clearly point out conflicts that are being avoided and users you aren't driving away.
- If you're working public web or app design, create more screens, pages or sliding content to maintain a minimal feel but increase project content visibility.
- Do some usability testing with outside parties