Do you think they possibly went in using the wrong aircraft? As MV mentioned average loads are around the 50's and i can't help but think that maybe they should have used a CRJ, versus the BAE which has another 30-40 seats....
Whilst the reduction appears a bit sudden, it is good to see that it is not a more severe cut and maybe LH can already see enough of a pattern to start to 'trim' the route to be more economical.
At least it has not been dropped all together.