at 60+lbs for most of these screens you need to secure them directly to a stud to mount them to a wall. Fixing the mounting holes to each corner of the bezel would almost guarantee that you would only ever get two screws and only on one side into studs leaving the other side hanging by only drywall which would subsequently rip out either immediately or over time placing all of the weight on the other two mounting screws which would effectively rip those two screws right through the bezel. Without the manufacturer putting adjustable slits into the bezel like they do on the wall mounts it would be nearly impossible to mount it securely and then it would look ugly.
And then, there's the fact that the bezel is not designed to hold the TV, it is purely decorative and it would be really easy for the customer to over tighten those screws and snap/crack the bezel. Maybe if the bezel was steel reinforced but that would add extra cost. What's the point when you can get a fixed position low profile wall mount that would accomplish the same thing from monoprice for $20?