In "Politics and the English Language," George Orwell argues that modern English writing lacks precision above all. It is plagued by clichés and vagueness, obscuring meaning.
As to why authors are using meaningless, vague prose, Orwell has a few theories. The first is incompetence, an inability to properly express what the author intends. The second is far more sinister: that writers want to obscure what they mean in order to make their ideas seem more palatable or authoritative.
For example, some writers use foreign words or "pretentious diction" in order to "give an air of scientific impartiality to biased judgements." These writers assume the ordinary reader will be impressed by large words and automatically assume that the writer using them is of great intelligence. For Orwell, it is essentially a cheap way of appealing to authority.
Another example Orwell uses is how politicians try to excuse violent war crimes, such as the bombing of innocent civilians. To label the action accurately puts the ruling government in a bad light, so politicians often use terms like pacification to put the violence out of the minds of their readers or listeners. The same applies to colonization and suppression of dissident opinions.
Orwell also calls particular attention to the use of the word fascism, once a term with a specific meaning and now only used to describe "something not desirable." The writer knows the word will trigger an emotional reaction, regardless of if it is being properly used or not.