An interesting conundrum here:
First, the obvious starting premise is that Hino and Koguma each have a very different image of themselves than the other one does: Koguma thinks of herself as childish-looking while Hino sees her as unbearably cute; Hino sees herself as plain and uninteresting-looking, while Koguma sees her as a cool, mature beauty. Changing those assumptions and perceiving themselves as "worthy" of the other one would be an important step towards an ultimate romantic relationship.
But if this is in fact some version of a dream or hallucination, the effects (seeing oneself as the other one sees her) will be perceived only by the "dreamer" (presumably Koguma after she hit her head).
So this event can only signal mutual "progress" if it "really" happens so that both come to understand how the other person sees them, and thus, as people have been saying, introducing an entirely new fantasy element to the series.
(That is, unless there's a way to explain away the apparent body switch and still have both of them feel the effects that I'm not thinking of here.)