1♠ has great preemptive effect. For instance you're LHO and you have Ax KJxx xx KQxxx, your call. Unless P also has a 4-card major with 10+ hcp ...-(1♦)-2♣-(p), your call ...-(1[CL)-1♦-(1♥)-2♣-(3♣)....pard is 4252 http://en.wikipedia.org/wiki/Drury_convention ...-(1NT)-P-(3NT), happy? 1♠ opening directs a good lead (leading is hard), preempts them out of the 1-level (bidding after opps open is usually harder), and won't get us too high since pard is a PH, and we're even NV at MPs so -1 or -2 may be a good score. Remove some of these horses and it's no longer a clear opener.