This seems to be a widely held understanding, but speaking just for myself, I just don't see it as all that important. Makes me feel dense.
Until we were able to provide verifiable evidence of extra solar system planets, they lived only in the domain of science fiction. Logic and understanding told us that they existed, but we could not put them up on the scoreboard until we had satisfied our scientific methods. Planets are being discovered in their thousands and thousands every day and year. Are some of they host to life? Of course, but until we can provide scientific proof in a verifiable fashion, it will remain science fiction. If Mars can produce the real homerun, then it will occur in my lifetime. Exciting.