Heyo!
For a bit of context, I'm QA on skins, so I don't have data to share on if they were successful or well received.
However, you may have seen some surveys popping up asking for feedback regarding chromas, and various other questions around them. We want to get a feel for how you guys perceive chromas, and what you'd ultimately like to see/get out of them. Right now, we're discussing chromas and what the best route/future for them is.
Personally, I think they're cool - I use the Nami chroma pack more than any of her other skins, honestly.
I think some champions may be better suited for them than others, just based on their models and what pieces should be changed in each chroma, but I don't think it would be impossible to create a chroma for each champion. By the end of the year would be a pretty tall order 'cause they'd be worked on alongside all of the other content we have planned for the year. :P