Uke means to receive. Imagine different cultures handling receiving a gift in different ways. For them, the way to receive and what to do when received or how to receive is defined culturally. Whether the way of receiving is good or bad is culturally determined. The point is, that each culture receives a gift in a way that they find appropriate. One can open a gift, one can put it away and open it later. There are many ways.
When receiving energy this is the same. The only difference is that combat is not culturally determined so one is not limited in how to receive the energy. There are only better or worse ways depending on the situation.
Nevertheless, in Wadoryu, there is no block. Any ukewaza is to attack. Also, for example jodan uke as practised in kata like pinan nidan is omote. Below an example of how to use jodan uke.
Basic ukewaza from kata should be studied carefully and deeply to see the (internal) dynamic of the movement. For example, in my opinion Hirate uke from Pinan Yondan and Kushanku holds elements that are similar to the second movement of kihon gumite ipponme. The dynamic of the body movement allows for applying hiki mae ashi in the process which becomes smooth and dynamic on the surface. Hence, it already is a dynamic movement, but looking at omote from kata it is difficult to see. Below some ohyo waza of how this dynamic can be applied to maegeri and jodanzuki.
images from N. Ishikawa sensei's book "way to the black belt"
KIHON 基本
