I don't mean to be harsh since I do like this game but it struck me that on subsequent playthroughs I'm not super motivated to get involved with the backgrounds/personal quests of a lot of the cast mostly due to the way the game is structured.
In LLTQ most of your scripted events involved members of nobility for example Brin, Kevin, Briony, etc which would naturally pique your interests in what the deal was with the characters and cause you to try on subsequent playthroughs to get the right stats to solve it.
Also flavourtext from your lessons helped because it worked as a hint system: internal affairs was the most obvious one but I remember knowing I could survive certain checks based on what the flavourtext told me about the new skills I picked up. The Basic-Student-Graduate-Expert-Grandmaster System doesn't tell the player at what levels they can expect to pass checks as intuitively as you need to run into the check and see what level was needed. In long live the queen I failed the first time I ran into the Brin causing border issues problem and it was later in the run when I started learning foreign affairs that I realised that she had caused the conflict in the first place, after the event had happened which obviously shaped my approach the second time.
Here, most characters you interact with once and you can frequently bypass actually learning about them by simply offering a council seat. Whilst there are moments that do make you want to dig into the background of certain characters (I'm looking Eve- wtf is up with her?) - by the games structure if something looks like it'll take longer than 2 turns to get to the bottom of its far easier to focus on the people that can have their vote secured in those 2 turns and quickly move on to the next sector.
Having information about characters locked behind social actions on the turns better spent grabbing council members or negotiating for votes actually disincentivises me in trying to dig into the background- with high empathy you can see how likely they will vote for you without actually interacting with them and then you can spend your social actions locking down the vote over wasting time exploring their background. Meanwhile in deep space you have far too many social actions and nothing to spend them on.
The first time I visited Heru IV I noted that people were hostile and it seemed it would take several skills I didn't have to figure out what their issue was. So on subsequent playthroughs I started avoiding Heru IV. By the time you've visited everyone, and locked down enough votes it's usually turn 31-33 which further reinforces that taking extra time for more intricate characters wouldn't have been worth the effort because there wasn't enough time to spare anyway.
My point is as you figure out how to win the game at its most basic (as in complete the main goal and win the necessary votes) you don't have enough time with the characters that don't confer to an easy vote to build up time to be more curious about them. You dont get like the 3 events where you run into Kevin so in future you start actually wanting to figure out what his issue is. You don't have a path where you've decided to go full Lumen and run into an option where you can hire your aunt then subsequently face a lack of assassins so that you start suspecting her on subsequent playthroughs etc. (Yes hiring certain councillors lowers the assassins but since there are multiple people trying to kill you it doesn't actually create a noticeable enough drop in attempts to help you conclude what's happened).
TL;DR : I find the scripted events don't involve the wider cast and the time pressure makes it harder for me to want to take interest in the wider cast. Instead my follow up playthroughs focus more on optimal council building/vote gathering and moving through the map because the large cast turns into voters that I dont have time to get to know.