If two different views are sharing the same model (for instance, maybe one is for mobile output and one is regular), it could be nice to have the string reside in a single place: as metadata on the ViewModel.
Additionally, if you had an inherited version of the model that necessitated a different display, it could be useful. For instance:
public class BaseViewModel
{
[Display(Name = "Basic Name")]
public virtual string Name { get; set; }
}
public class OtherViewModel : BaseViewModel
{
[Display(Name = "Customized Inherited Name")]
public override string Name { get; set; }
}
I'll admit that that example is pretty contrived...
Those are the best arguments in favor of using the attribute that I can come up with. My personal opinion is that, for the most part, that sort of thing is best left to the markup.