Quoting Matsui vis Camate:

Not only Ochain, but all existing shields will still have their same block rate as usual.

Other shields will not have a block rate that gets close to Ochain; however, there will be shields that have a higher damage reduction when blocking than Ochain.

More than just preserving Ochain, it's that we are in a situation where Ochain adjustments are extremely difficult due to the fact that strategies that involve the use of Ochain are well-established.

If we were to convert the block rate of Ochain into terms of item level, it would just about be item level 150. In the case we were to reduce the stats to something more proportionate (consider RME weapons), it would be tied to increased difficulties in Delve plasm farming and such.

If this is what is wanted, we can always take a look at reducing the block rate on Ochain; however, I don't believe you'd want this, and neither do I.

We'd like to avoid the consequences of nerfing Ochain, and have selected to add stats to shields we introduce here on out so they can gradually get closer to the stats of Ochain. If anything is unclear with these intentions, please let me know.
As shields, including ochain, stood. Blocking would have been bad for anything but shields with lots of shield skill on them. They're making changes to so that shields continue to block at their intended rates.