I summarize here [1], you can find more context here [2], and learn more about the differences here [3]. For a detailed explanation of the new design see the video talk above.

[1] https://news.ycombinator.com/item?id=40483749

[2] https://www.reddit.com/r/Freenet/comments/1d05zw9/questions_...

[3] https://freenet.org/faq#faq-3

I see reasons listed for the rearchitecture but not the "rebrand".

Same thing.

Only if you want to confuse and mislead everyone.