Used to riding with my Onza titanium L-bend bar-ends, I was made to believe that the correct handlebar width should be just a tad bit longer (about a couple of inches more) than the width of your shoulder. That's it. Other than that and it gets sawed off. This explains why, during those days, some handlebars come with printed marks to make it easier to cut.
After riding my Intense Tracer VP for about a year, I didn't realize how I different the ride was when I used the hardtail again in our La Mesa ride. More than the harshness when I hit the bumps, it's the narrow handlebar width that made the bike handle differently. It may just be me, but I find flicking the bike on the singletracks a bit harder to do compared to the Intense. Maybe it's the lack of bar-ends that made it feel weird (I didn't install it for this ride). I don't know.
Now, I'm thinking if it's worth the effort in switching my old Truvativ Team flat handlebar with something that's wider and has a more hand-friendly angle. I don't ride the hardtail as much. Maybe I should just save the money for a 27.5.