I disagree with the parts in bold.
Regarding the 'sacking of established voice actors', I'm assuming you're referring to Glynnis Talken being replaced by Tricia Helfer. To say that Talken is an established voice actor would be inaccurate. If you look at her
IMDb page, she has been credited with five voice-acting roles. Helfer, meanwhile, has been
credited with more voice-acting roles (with more of them being high profile ones), in addition to more acting roles in general, in a shorter period of time. Therefore, objectively, Tricia Helfer is a stronger and more experienced performer. If anything, the main 'problem' with Blizzard's decision is that they essentially discarded a long-time associate (four of Talken's five credits are in Blizzard games) in favour of something new and shiny.