My understanding of the regulations is that if the manufacturer does not or can not certify that the aircraft can land above MLW with a RoD less than 360 ft/min without structural damage, then a fuel jettisoning system must be installed. Hence, the very large long haul machinery needs to jettison because at MTOW they are substantially above their MLW.
By that logic, if the aircraft has a MTOW greater than MLW and it does not have a fuel jettisoning system, then landings are safe up to MTOW provided the RoD is controlled.
As many have said, you will not burst into flames immediately on impact if you are above MLW. Even if you land heavily while at MTOW, you will cause structural damage, but that does not mean that the wings fall off or the wheels go bouncing across the perimeter road and over the fence. I would much rather risk a technically written off fuselage than hang around in a hold on one engine for an hour or two while I burn off fuel. I would be inclined to add any failure, other than trivial ones to my list of failures that would warrant an overweight return.
Give me hydraulic trouble, electrical problems, engine problems, or of course the smoke or fire and I'll go back heavy every time.