Also, they thought that if any other planes landed on the Island that then they would have a safer landing.
It is not likely that built the runway for flight 815 because it was a surprise when it crashed, flight 815 crashed over the main island and it was still being built when Jack, Kate and Sawyer were taken by the Others.
The others seen the future and seen that flight 815 was going to crash but didn't know when so the started a runway but didn't finish it in time even thought they seemed surprised some things they see in the future aren't true. So when the second plane crash happened the runway was ready although they expected the plane to be smaller"maybe the runway was built for the Beechcraft.
815 broke up in mid-air, so having a runway wouldn't have helped them land safely even if they had finished it in time.
The Runway Was Always Meant for Ajira 316
Jacob ordered the runway to be built because he knew who would be arriving on Flight 316: all of his "Statue" friends.
Also the Oceanic 5 + Ben & DeadLocke, whom he always planned on coming to the island on that plane.
Ben has never met Jacob, so the only plausible person who could communicate this request would be Richard.