I will be the buzzkill to this obviously silly question thread.
The reason his dialogue is ‘sad’ is because all he knows in life is combat and warfare. From the age of seven, when he was kidnapped/conscripted into the Spartan-II program, he has learned how to hurt, maim, and kill. His only family has been the other Spartan-IIs, and he has, over the course of his life/career, watched nearly all of them die to his enemies.
As we see in Halo 4, ONI views the Chief as ‘broken’, and that isn’t far from the truth from a ‘human’ standpoint. That is one of the hidden themes of nearly every story we’ve seen with the Chief; he is ‘growing’ as a person by making more ‘human’ decisions that do not just extend to his immediate Spartan-II family. In the Fall of Reach, we see his initial connection with Cortana, the importance of the Spartan-II family and the unspoken bond between the Chief and Halsey who is arguably the closest thing to a mother that he has ever had. We see the augmentation process which pushed the Spartan-IIs beyond baseline Humanity, and watched more of his ‘family’ die or become so horribly changed that they were unsuited to further serve.
In First Strike, the Chief is given a choice on whether or not to hand over data concerning how Sgt. Johnson survived the Flood. Handing over the data (which was the strategic choice) would have had Sgt. Johnson killed in the name of science, with the miniscule hope of figuring out his immunity. Over the course of the novel, and due to the events on Alpha Halo, the Chief slowly changes his mind as he comes to consider Sgt. Johnson more than just a ‘human’ soldier, but as a friend. This is something we see continued in Halo 2 and 3, which is why (however hamfisted it might have been handled) Johnson’s death in Halo 3 is so tragic.
And in Halo 4, there’s the relationship between the Chief and Cortana. Whether or not the Chief had a ‘romantic’ interest in Cortana (I see it more as a brother/sister relationship), her rapid decline and eventual death led him to buck orders against a superior officer (following the chain of command being almost instinct for him since childhood). The Chief is a war hero, and the Halo 4 era is arguably ‘peace time’. You see the tentative bonds of friendship being formed with Captain Lasky and Commander Palmer, much like they were formed with Johnson, but we have yet to see where those roads lead.
Halo’s story, as much as it is about Humanity fighting space aliens, is about the Chief regaining his humanity. That is why his dialogue is ‘sad’. All his life he watched those he considered family die in combat, and has never known what it was like to be more than a tool of war.
Will John-117’s story end on a sad note? I don’t believe it will. The Reclaimer trilogy just isn’t about Humanity taking up the role that was intended for them, this is about John Reclaiming the Humanity that had been taken from him at age seven.
I’m honestly hoping that he does complete his storyline by the end of the third 343i game, and that he can either die as a Human and not a Machine, or he can be properly removed from the picture without teasing at his return in some future game.
As for his medals, the ‘home base’ for Spartan-IIs was Reach. We can assume that whatever medals he was awarded were done in secret or not even acknowledged until the Spartan-II program went public for morale purposes were kept there and were subsequently destroyed when Reach was glassed. The Spartan-IIs were indoctrinated to not need the pomp and circumstance that came with being awarded medals for their service. Their own reward was satisfaction for accomplishing a mission and the safe return of all other Spartan-IIs that returned from said mission. As for the medal he received during the opening events of Halo 2, he most likely discarded it in the brief flash between the cutscene and the jump to gameplay. Or, as you said, lost in orbit when he delivered the antimatter bomb or when he was retrieved by the In Amber Clad. Or discarded during combat prep for the fight in New Mombasa.