I was irritated to find that such a sublime experience was cut short just as it approached transcendent for me, but I've spent the day since finishing my first playthrough reflecting on the meaning of the game itself, and realizing that despite the identical environments, the game was designed for multiple playthroughs because the improvised interaction and companionship are a huge part of what made the experience worthwhile. If anything, repeated playthroughs will focus even more on this aspect, because the unfamiliar environment won't distract from the focus and empathy on what your companion might be thinking. Having read a bit about what subsequent playthroughs are like, it's clear that this is by design, with subtle cues that help you recognize when you're playing with people who are on the second round through instead of the first, and interesting reactions in yourself to those two different situations. (I was actually confused that seemingly well-developed communication patterns were suddenly ignored by my companion, not paying close enough attention to notice that the person I was with had changed between sections.)

It makes the game itself a yet more beautiful a mediation on life itself. Per the old saw, it's not the destination but the journey, etc... and given the journey matters so much, then really the best thing we can do while alive is savor the company and attempt deeper communication with those who we so fleetingly meet, whether we fall in love or go our separate ways, and not focus on where we end up. It's not a new thought, but I feel it more profoundly and presently after playing this game than ever before... even in the moments of deepest grief after my mother died.

I'd say the "can games be art" debate can pretty much be put behind us now.