You can't justify doing any kind of basic research without some sort of theory or question or simple academic interest. Even basic undirected research isn't utterly random. Someone has to have some sort of idea they want to investigate. "Is it possible that there might be other environments similar enough to our own that they might be inhabited, or habitable, by anything, not necessarily us nor excluding us?" is no more or less a basis for science than say documenting the funny structure of the powder/scales on butterfly wings, initially just because someone finds it interesting, but of course everything, including that, ends up being useful and valuable sooner or later.

It IS fun to think about, but this is not a crime, or even merely silly or pointless, and wasn't at any time let alone "with todays technology".