If you think about it, the whole RTS arc covered in the current season is commentary on the series as a whole.
Armin's narration at the beginning of s3 pt2 discusses the uncertainty that'll follow when they retake Wall Maria. How will humanity (or more specifically the viewer) react to the truth and whether they deserve to live.
The series started out seeing the titans as an unstoppable force of nature that has no reason for it's actions vs humanity, one of the main attractions of this series. People die left and right, yet their death's are said over and over to have meaning. Contrast Armin's ambiguous but hopeful message and with Zeke's condemnation of our heroes' tactics. In every operation, both titan and human, many soldiers have lost their lives until 9 people remained in the Survey Corps. Zeke, in a brief moment of anger and half hearted compassion, gets angry about this saying that, in his mind, because they believed this to be heroic, they'll send everyone in the walls to their deaths. Up till this point, the viewer sees the recapture of Wall Maria and the basement as the answer we've been waiting for. From Floch's POV, however, what was so heroic about charging towards certain death and realizing that you're the only survivor? Marlo's character represents the view that the Survey Corps are the good guys and wants to help others, but fails to realize that there are people at home who are concerned about his safety. When we reach the basement, suddenly the whole story that we've been following seems very small in comparison to what's now at stake.
As the series goes on, however, the portrayal of the titans slowly changes, and may explain why some people may have found s2 onwards to not have the lasting cultural influence of s1, with s2 ep 6 being the main dividing point. From that point onwards, the titans lost their effect as a force of nature and slowly became instruments to be manipulated by human enemies. The revelation to Eren that the enemies he hates are his buddies that helped train him in the military and gave him confidence. Erwin leading a horde of titans against the armored titan. The gradual realization that mindless titans were once humans. The king kept the people ignorant about the world. Sure people will still die from the mindless titans, but the effect of their loss feels different from the horror that was in s1. In this season, they're barely seen up close, with nearly all of them being commanded by the beast titan to blockade the scouts or to lure the scouts towards the front. The ones that are not part of Zeke's army are depicted as victims of human excess and greed.
Probably the most damning commentary is Gross's speech to Grisha on why he enjoys turning Eldian's into titans. His personality and actions are horrific beyond comprehension, nevertheless he has his own view of the truth of the world. He represents the basest urges of greed and excess and he gives us a view of the series from that lens. He's bored because there are no enemies to fight and to us, the mindless titans are gone.There are none left to pose a threat and we feel only sorrow towards the ones that are there like the one encountered on the way towards the ocean. We see Levi use the titans to reach Zeke and return, but by now we have no reason to believe he's screwed since he's Levi, humanity's strongest soldier. What's there to interest people on a series that has long since left one of it's main appeals. To rephrase this, how much do we, the viewers, really care about the individual lives of these characters? Is it really enjoyable to watch characters succeed against the odds or die with no purpose ways. Are we just interested in this series because of it's concept on humanity against an unstoppable force? Gross doesn't care that he's doing something evil as he's distant from his actions. So long as it's not happening to him, why should he care?