To me, there is just so much more bad that can come out of a conference call versus just issuing a PR.
Only reason to have a call is if it is open to questions, actual live questions on the call, otherwise you are better off just issuing a PR.
I think they are doing a conference call to avoid having to put out anything in writing that can be read over and dissected. Easier to spew out nonsense to keep the investor base placated.