Wonder what brought that on? Detrimental in all kinds of ways for pilot development, CRM, safety. As Sir Korsky points out though there are some controls on the right, which drives the right-seat only single pilot limitation. Multi-crew we never found it a problem to put the SIC in the right seat, and in our company you could fly PIC or SIC from right or left for whim or reason. For a tough left side landing offshore at night on a pitching deck you'd be damn sure the experienced guy sat on the left for the whole trip.