A hypothesis doesn't need evidence, it only needs to be falsifiable. But you're right, there probably will never be any evidence to form a theory with regard to the question of alien contact in the near future anyway.

I personally wouldn't tell scientist what to do with their time. After all, I'm just a redditor. Furthermore, it's probably just a minority of scientists who can afford researching outlandish topics like this one, but people and pop-science journals love those. And I have to admit it's a fun and quick sci-fi read.