I prefer it all vague. When I was a kid in the 1960s, with NASA's Apollo missions enjoying such great success, I honestly thought we might be living in the TOS era by now.
What's wrong with not knowing? I really don't like, for example, having an explanation for every last part of the warp engines today. Mystery is a big part of what attracted we first TOSers.
I don't know how I can explain the feeling back then. You might be familiar with modern sit-coms with two characters who contemplate a relationship, such as "30 Rock." That adds a "will they or won't they" dynamic. When TOS first aired, we had a similar dynamic: how soon? Will we live to see it? Will our children?
TMoST makes this very clear; there were some fans who even thought TOS was secretly underwritten by the government to prepare us for pending alien contact. Looking back, that was pure crazy. But it's how some thought of TOS at the time. We were that hopeful about the future of humanity in space.
Sigh . . . "were."