I would also be really keen to have this batch style update/delete support added to the framework.
However I think performance is the leading driver for adding this type of query. I have done some tests on the EF Extended and found that the performance was quite poor. I think this would be an amazing (and much requested) feature to add in so long as we can ensure it performs faster than a regular EF delete query.
I would be really keen to contribute to this code.