I think because the channelers in Seanchan are leashed, they don't get the kind of training that would foster creativity and independence. Remember the discussion about Alivia? She's VERY gifted in the limited areas the Seanchan use their damane for, but in any other area, she knows NOTHING. A damane doesn't get the kind of training the WT gives and doesn't have the freedom to learn her own tricks or experiment the way that every girl who comes to the WT does.