I know my comment won't be as helpful as others but I agree with so much of everything being said here. Slice of Life is fun but there needs an extra element these days to get me interested. I'm just going to echo a lot of what's been said here but the whole "searching for a romantic line only" thing has gotta stop because I've fallen victim to that again and again where my character would have a really interesting non-romantic relationship with someone and as soon as they get into a relationship it's game over.
I do wish that there were more games where mods have certain things that happen that would completely affect the lives of all characters. I've been in groups where that happens once or twice and then the mods kind of give up on it, either because they lose interest or because those in the group aren't having their characters fully react to said events. I think the mods would have to be very involved and I think it would have to be mandatory for those in the group to have some sort of realistic reaction to what's going on within the game instead of staying in their little bubble.
It also makes sense to me that maybe a smaller group instead of a large community might be best. All people who are really dedicated to making the game something special, you know? Activity is an issue as well with larger communities, posting every now and then isn't going to help move anything along. If there could be a larger group of very dedicated people, then that's awesome! But I feel like the bigger it gets the harder it is to keep everyone focused. I might be wrong about that, maybe you'd just need to attract the right people?
Maybe a promise of a special "surprise event" or something like that for each character might help? If the mods were involved enough and paying attention to different plots then perhaps something like that could work? Like say a character is a bus driver(totally random lol) and suddenly one day there's a high speed car chase and the bus gets ran into. That's a significant plot point for that character. Or there's a tornado/really bad storm that comes through the city and takes out a restaurant that some of the characters work at. Now they're out of jobs and have to find something else. Those are just really basic examples off the top of my head but I've always thought events like that keep things interesting and personally for me, if something like that was out of my hands and my character had to adapt to it, I'd be totally excited for it.
Those are just my opinions of course! I've never modded a rpg in my life but I've been part of so many and if you ever do think of starting something up and need help or ideas, feel free to track me down! I've been dying to some kind of creative release in rp these days.