Of all the things wrong with this episode, that line is the last thing that bothers me.
In fact, the existence of what I call humans with funny ears in the Delta quadrant is much more disturbing, and the scene where Janeway shows the ears of Kes to the 37s is so wrong. Why would you put a scene which only highlights the ridiculousness of the notion – it's so ridiculous that even the characters didn't buy it, and you're expecting the viewers to buy it?
The reason Spock's ears were fine in “The City on the Edge of Forever” was because it was
funny. This wasn't. The reason Spock's ears were fine in “Tomorrow is Yesterday” and “The Voyage Home” is that the hint was
subtle and open for interpretation. This was neither, and being delivered by the Janeway in lecturing mood made it even worse, because I can imagine Shatner delivering the same lines and making me crack a smile. A completely pointless lines which only served to exacerbate a flaw, and to create an awkward situation (for the show, the viewers and perhaps Janeway) which served no real purpose.
The 37s is one of the many episodes in my list of episodes that could have been great because they took the liberty to create an impossible and thrilling situation, but in the end completely missed the opportunity to take advantage of it and turned out to be a mess. I watched it quite a few times because I love exactly this kind of unanticipated set-ups, but unfortunately it didn't go anywhere.
And, frankly, I agree that I would take the “only humans” line off the episode if I were to make a list of the things that need to be fixed in it. There's simply no need to draw any attention to this. Either make it subtle or make it comical.
tl;dr - I love first contacts, time travel, alien abductions, and Earth-shattering discoveries. Why do most such episodes suck?
