If champions can see her if she gets close, then what's the point of her passive? See how that's not really an argument?
Champions have their sight radius, and evelynn can be in that without being visible.
Her visibility is determined by how close she is to you. I am not saying that stealth wards should straight up reveal her. Obviously, that would mean that her passive was pointless. I am saying that they should reveal her, if she passes close enough to one for it to be in her 'reveal bubble.' Like I said in the OP.
Basically, I think evelynn's stealth should treat wards as champions when it comes to her visibility. That means she is visible to the enemy team when she gets close to one, and she is notified that she is visible to the enemy team while that happens.
The point of her passive is to be able to have freedom in choosing who you fight. Another reason for her passive is to make people's attempts to prepare for your ganks less effective. The wrong way to go with evelynn is to make it so her ganks aren't something you need to be prepared for.
Evelynn previously had counterplay because although you couldn't stop her from stealthing, she couldn't stop you from getting vision unless she or one of her teammates bought a vision ward theirself. Evelynn's passive has less counterplay now because she and her teammates can get rid of your vision wards for free. It has some counterplay in that she now has to take the time to destroy your ward instead of simply waiting for it to time out, and she has to leave stealth for a longer time if she wants to destroy your ward.
I can see how this could be a sort of awkward buff, wherein evelynn's team uses her like a ward detector, however, they would still have to use their trinkets or place a vision ward in order to destroy it. A possible limiter on it could be that evelynn is destealthed whenever a ward is responsible for revealing her.