No! It would not be a good idea to limit two drinks to pax in flight. Why punish someone like me, who enjoys several drinks (especially on a long flight) and always keeps to myself and doesn't bother a soul?
Last year I flew a late night mid con flight in first class, and of course enjoyed several drinks. There was a man sitting across the aisle from me, one row back, who was just obnoxiously loud, arrogant, and everyone in the entire fc cabin heard him chat away to his seatmate, bragging of all his successes and accomplishments in life! This guy thought he was a showboat, and wouldn't shut up. What was he drinking? Continuous refills of black coffee!
Furthermore, if such a silly idea of limiting pax to two drinks on a flight became reality, would airport bars also be forced to enact the same? If not, I'm sure binge drinking would increase tremendously before getting on the plane.