So the complaint from the LC$ neckbeards is that you can't punish her because of W, and she makes that super balanced Aatrox or other juggernaut unkillable (as if they weren't already). The complaint from the rest of the community is that she's annoying... but then Yasuo exists, so that's not really a unique problem.
Anyway, here's an idea on making her a bit more interactive without gutting her repeatedly, and encourages her to detach every now and then.
**The longer you spend sitting on someone in your W, the weaker your E gets (down to maybe 50% effectiveness). This does not apply if your shield is active.** This makes it harder to solo carry with a Yuumi attached to you, and makes Yuumi have to actually interact with you in order to maintain her healing. This would have a separate effect per allied champ, and you could have some kind of indicator to show it.
But if we're making her rely on her passive more, we need to tweak her passive a bit too, right?
**While your passive is on CD (and no shield is active), empowered Q hits and auto attacks will lower the CD by 1-2s.** This gives Yuumi a reason to detach in lane (though poking is already a good reason, but now there's a reward for it too), and would give you opportunities to punish her in lane.
And maybe we can give her back a bit of mana restoration with this: **When your shield absorbs its full value, you gain X mana.**
**And then, finally, add a 2/1/0s delay before you can re-attach to someone you jumped off of (scaling like her W CD already does).
From there you can tweak numbers and buff / nerf things that need buffs / nerfs, but I feel like these changes make her much more interactive without significantly changing her playstyle, and entices activity rather than being AFK.