Aside from giving you much more immersion and variety (as current Eve’s universe seems extremely monotonous/boring to the eye, a cold totally generic in all directions place I just can’t feel I belong to), it could have some really neat things packaged with it. Like, a different kinds of gambling activities tied tightly to in-games mechanics (what is not possible with 3rd party sites where you can make bets with isks I know exist). Like, how about a poker match with sov claim or citadel ownership at stakes? Or how about playing mahjong with your titan alt as a stake? There also could be some simple dueling system (on foot, not in the ship) with its own mechanics totally different from the usual “submarine ships” mechanics, so you could have some rest from it a bit - with the same ability to make a stake with your Eve’s assets, and ensure you’ll receive it if you’ll win. It also could bring some tools to reach those certain players who stay docked most of the time, hiding from righteous retribution from their foes, at last (judging from early WiS trailers they indeed planned something like this, as there was a scene of assassination inside station)
You can come up with tons of content which will “lure” people into this system. You can also implement it in such way that those people won’t need to dock to participate. We are in a distant future, so virtual reality is the thing. You can grind your rocks at belt for hours while walking in virtual station room, among those who are physically present there, or, say, lore may say you sort of using a temporary remotely controlled clone for that, similar to what DUST mercs used. So inside of your main client’s window you would just have another WiS window where you would be able to walk around and play poker while autopiloting along 30 jumps route through hs.
Tons of options, they just needed to actually try.