I think that this is because people want to answer the question definitively. Currently there is not enough information to create a strong consensus on the test

I think that this is because people want to answer the question definitively. Currently there is not enough information to create a strong consensus on the tests and evidence required to say that there is / is not life present. The idea of the exploratory program is to move to a point where the community says : we need to do x and then that will settle this pretty clearly. Then we can do x.