This is common with writers, and you'll often see it with people like singers as well. I suppose you can think of it as putting the person's living status aside, when it's not really relevant, or if you don't want to emphasise the fact that someone's dead.
When you listen to a recording of a song, the singer is performing it for you at that moment. And when you engage with a written work, the words "speak" to you from the page. It's happening now, when you're listening or reading or whatever. The writer is expressing ideas to you in the current moment.
All books were written in the past, all songs were recorded in the past, so using the past tense isn't really giving the listener any additional information, you know? You can definitely use the past tense to emphasise the fact something was done in the past, to locate it at a specific point in history, or to highlight the fact that a person has died. But when you're just talking about a person's work, you can use past or present interchangeably.
And using the present tense for everything puts it on an equal level - all ideas for consideration, nothing is implied to be dated or superseded by later work. That's probably a reason you'll hear it in academic settings.