I have also noticed this in recent years. It must stop. It has spread now to non-journalists, like some kind of virus. Even a neighbour of mine pronounced 'Western' as 'Weshtern'. He said it multiple times in one sentence and so I stopped him, and asked, "Are you saying 'Weshtern?'" ... He smiled, like he knew he had been caught doing it on purpose and admitted, "yeah". I then asked him why, and he shrugged. Weirdo.