I am a huge lore junky, and i generally like it when in game characters have some history rooted in the existing lore. But the new champions Riot has brought out these couple of months are in no way bothering me. As a matter of fact, I totally ADORE Kindred and everything that they represent, just like Tahm Kench. These are beings that maybe did not exist in the lore up until now, but enrich it non the less. They give Valoran a certain realness...These are beings of Folklore, just like Krampus (Evil german santa) or werewolves. They represent something in the history of a people and I personally love this kind of stuff.
As for the others: Illaoi opens up a whole new place from which champions or maps could come from. The Serpent Isles haven't really been explored as much as other places like Bilgewater or The Freljord have been. Bard....well yea Bard does not really make sense to me either, but it totally fits with the style in which LoL's lore has been built, as in....it doesn't seem like it has no place to be there.
I don't think that there will ever be a champion with a lore entwined with other champion as much as Lucians wife would have. I would personally think it wouldn't do both Lucian and Thresh any good lore wise if she just showed up one day. It wouldn't be original and Lucian would need a new drive to fight. The fact that Thresh took his wife is such a big part of his character that Riot would have to throw away everything he is. Besides, although you might like it if this happens, there would be a lot of people screaming that Riot is running out of ideas and are just using already existing characters.
All in all, I really like the new champions and in the end its merely a matter of personal taste. I hope to have stirred your thoughts a little with this post :)