One way I think they could have tackled no-one seeming to care about Earth any more in Starfield is to make it almost a taboo subject in Settled Systems culture. The collective trauma was so great it led almost to a collective chosen amnesia - stories about Earth are tolerated for basic education and children (like Cora, who has a horse girl phase ofc), but are otherwise considered inappropriate for adults to dwell upon too much. Let the Earth Savior Award be pretty controversial, and the rich folks on the Siren of the Stars be considered eccentric, and even with a measure of disgust by the service people and pirates we talk to. The Terran Preservation society should be banned in most places - hence why they do their 'work' in space.
Have people who we meet living somewhere like Mars who are shunned for being 'Earth obsessed,' a kind of depression brought on by a deep, half-remembered loss and characterised by odd behaviours - I'm thinking in the vein of the The Expanse, with the XO treading upon soil he'd tipped on the ground. Let us meet a doctor who is seriously studying a kind of old Earth psychosis. Let us help a guy who has barricaded himself in his room surrounded by posters of old Earth, pictures and inaccurate diagrams. Going mad, lost in memories that aren't really his own.
Have there be a belief that setting foot on Earth is bad luck, or brings some kind of curse, with urban legends about people who have done so.
And let us meet the people who DO care, the genuine members of the Terran Preservation Society that think humanity is losing something important. Let us make the deciding vote in a debate about implementing an Earth memorial day, hunt out old Earth artefacts and documents. I'd like to read or uncover some accounts - real harrowing stuff - about the high suicide rates following landfall, about children who couldn't get their parents to talk about where they were from, about teachers being unable or unwilling to teach properly. Similarly, I'd like to meet people who prove the point of those who think it's an inappropriate or even dangerous interest for adults: a cult trying to establish themselves in a hab on earth, despite the risk of asteroid strike. An oddly run business organisation that specialises in arranging burials who people who want to return to earth in death. Odd seeming people who dress in old earth clothes and try to live as their ancestors did, often inaccurately and at their own expense.
No-one seems to care about Earth in Starfield. Either they should, or there should be appropriate justification shown for why they no longer want to.
