If you idle long enough in the Great Temple's Energy Controller Room, U-Mos will play with the moths in the room by summoning a ball of light. It makes you wonder if the Luminoth kept those moths as pets...
He might simply feel a kinship with them, or perhaps sees them as his ancestors. Perhaps he sees it as playing with the grandparents?
Over the course of the game, Samus becomes the champion of the Luminoth and one could say, their deity when she obtains the Light Suit, essentially becoming one with the light of Aether. She's momentarily leaving her Chozo heritage and legacy behind to give the Luminoth hope.
The fact the Luminoth are actually grateful to Samus for everything she's done for them. Even the dead ones show respect to Samus for her heroics!
At this point its practically a day at the office for Samus to save an entire planet and save an entire civilization. Yet as she walks off, she waves goodbye...
What's really great about this is that Samus was finally able to save one of the advanced precursor species. We still don't know what's going on with the Chozo, whatever sane civilization on Bryyo among the Reptilicus has all but died out, and the Alimbic were victims of their own hubris, but at last some remnant of the past civilizations has been allowed to prosper again. Samus may sometimes be a Destructive Savior, but her heart is in the right place, and she's very humble about the major feat she was able to accomplish for the Luminoth at large.
In Prime 3: Corruption
In SkyTown, you can access an observatory and scan numerous planets, including Tallon IV and Aether. In the case of those two, you'll learn that Tallon IV is recovering from the Phazon infestation, and the Luminoth are rebuilding their civilization on Aether. Feels good to know that Samus really made a difference on those two worlds, and that she can save planets just as well as she can blow them up.
After defeating Dark Samus and destroying Phaaze, Samus takes the time to travel back to SkyTown. There, she disembarks, deactivates her helmet, and sits down at the landing pad, where she thinks back to her bounty-hunter colleagues—specifically not as Dark Samus's pawns, but mainly as the professionals they used to be. Something about the scene—a hardened bounty hunter who saved the galaxy many times, taking the opportunity to silently mourn people she knew only briefly—is just incredibly human, especially for a Nintendo-IP game.
Meta-example: You'd think after so long between proper installments, the fanbase would lose its mind at Prime 4 being scrapped and starting from scratch with a new developer. But when Nintendo made the announcement that they cancelled the build that was in progress because they didn't believe it would be a worthy product, the fanbase were by and large very understanding and accepting. Given how insane some fandoms can get, it shows how much faith Metroid fans have in Nintendo to wait until a product is finished good and proper.