Mage Update, Champion Niches, and Rylai's Crystal Scepter

So I'm really excited to see how the midseason update for a while, but I wanted to draw attention to one thing that is not being looked at for the update and removes some strategic niche from champions: Rylai's Crystal Scepter.

Does Rylais remove a champion’s strategic niche?

With the recently revealed rework to Brand, Riot has stated that they wanted him to be less capable of bursting out a target and more focused around shredding tanks and doing massive damage in teamfights. Similarly, with the Viktor updates on PBE, he does less damage upfront and more over time. Both of these champions commonly build Rylais very early in their builds, in order to keep champions locked down to deal more damage. Then why pick one over the other when they serve the same role? (Other than waveclear, I guess, which Viktor was nerfed for)

Imagine if Rylais were not an option - then Brand and Viktor could be differentiated by the amount of CC they provided and how reliable they were in getting their damage off. Brand wouldn’t be as able to reliably land his stun, but to compensate, he gets more damage. (justifying the %health dot)

Are there champions balanced around Rylais?

Brand is arguably one of the best abusers of Rylais, being able to proc a 40% slow off his W and refreshing the slow with his passive. But it’s unrealistic to think that Riot balanced him around this item. Are there champions that Riot does not want to give stronger abilities because they work too well with Rylais? Zyra is particularly concerning to me, with her rework giving more access to plants, she is able to slow nearly everything that gets close to her. But are champions like Zyra being “punished” for not building Rylais?

Does the statline on Rylais make sense?

Strategically, Rylais should be built on champions that tend to stay at range and kite opponents out. This seems like it would work with with an item that provides movespeed, not health. Unfortunately, this doesn’t solve the above problems and conflicts with the niche of Luden’s Echo, but it seems important to bring up, especially with the AP item reworks. Some champions build RoA + Rylais, which probably kills off the niche of the new Hextech GLP-800. The number of AP items that give health and AP seems to be getting oversaturated, especially when some of them work so well together. (I’m looking at you Rylais/Liandry)

Looking forward to hearing some thoughts on this