Cathay Swaps Batch of Airbus A350-1000s to Smaller -900

Cathay is getting their clock cleaned by competition from low fare airlines and the Middle East carriers offering Cathay level service at "oil money" subsidized prices.

The airline has recently solved the problem of too much management, not enough workers and is now working to make hardware conform to the real travel needs of the area.

The need to trim the budgets to eliminate losses is evident in the change to a -900 variant.

I don't know why companies are downgrading from a good aircraft. My opinion is that A350-1000 is much better than -900.
Might there be some reason behind this...