Hughes Helicopters actually looked at a parachute design in the early eighties. The static mast design of the main rotor would allow a parachute to be fitted above the rotor and it would not rotate when deployed. The real problem was the failure mode analysis. Should the chute be inadvertantly deployed by the crew, or should some failure in the design cause the chute to deploy the results in powered flight could be catastrophic. Then there is the matter of an unguided, non-steerable chute with a helicopter swinging underneath. There is the small matter of persons and property on the surface.
The parachute design on the MD500 was not a matter of 'can we' because it was possible to deploy a chute and land at survivable vertical and horizontal velocities; but 'should we'.