I absolutely agree that flexibility is the way to go. I also have to admit that a large part of what makes me function better in the office is that my coworkers are there as well. As such, I think a compromise that everyone can be as happy as possible with is the best thing.
Remember: Some people would prefer to work from home everyday, and function best when the do. People like me would prefer that as many as possible people are in the office as often as possible, and function best when that is the case. The optimum (both regarding satisfaction and productivity) is clearly somewhere in-between.
That means flexibility is very important, but “full flexibility”, i.e. everyone always working from where they would prefer, is probably not the global optimum.