Why change arena rank reward gems to seeds?

[Silent follower]

edit #2: didn't notice that they sliced duration from 7 days to 4; I wonder if next they'll also move and shorten arena to the same 4 days per week, so people can "fully concentrate on raid/war during the weekend without distractions from epic boss and arena"...

And they've increased the EB stats, Attack is twice the previous and defense 1.5 times the previous, HPs seem to have stayed the same. This I noticed from EB 25, which I exected to clear alone as I've done for a long time now.