Given that the book is being published by a major publisher, it can safely be assumed that the cover design was made by a professional cover designer, who knew what they were doing.
Contrary to what you wrote, the title has a bigger font size than both the subtitle and the authors’ names (this is true of both the American and UK covers; I am primarily talking about the American cover, which I presume is the one you are referencing). Even if the author names were the same size as the title, it is immediately obvious which one is the title, and which one isn’t. Putting the subtitle in a dark grey, which is much closer to the background color (black) than the color of the title (white) is, also does a lot to move emphasis towards the title of the book (away from the subtitle)
Most importantly, the title is plenty big. If it was small, then I would feel there is something to what you are saying; but the title is quite large and readable from a distance, and clearly delineated from the rest of the text on the cover.
In this case, part of the point of publishing a book (including writing it in the first place), is presumably to promote the identity of the authors, to make them a known name / schelling point for discussion about AI safety. That would indicate making the names quite prominent on the cover.
I see that the numbers indicate people disagree with this post. Since there are several clauses, it’s hard to know which specifically (or all of them) are being disagreed with.
The second paragraph (beginning “Contrary to what you wrote...”) is a list of factual statements, which as far as I can tell are all correct.
The third paragraph (“Most importantly, the title is plenty big...”) is more subjective, but I’m currently not imagining that anyone is disagreeing with that paragraph (that is, that anyone thinks “actually, the title is too small”).
The fourth paragraph (“In this case, part of the point...”) is more speculative, and I could easily imagine someone reading it and thinking “that’s not the point of publishing / writing a book”. There’s certainly a reason I put a “presumably” in there. I do still feel that there’s something to what I’m saying in that paragraph. My surprise would be of a limited extent if Soares and Yudkowsky said “that was not a consideration in our decision to do this”—but I would be somewhat surprised.
I can see someone disagreeing with the first paragraph (“Given that the book...”), but my current state of mind is that such people would be simply wrong. The book is not being self-published, but is being published by Little, Brown and Company. Some excerpts from Wikipedia’s article on Little, Brown and Company:
and
The point being, the company that is publishing Soares and Yudkowsky’s book, is an established company that has sold important and/or bestselling works for two centuries. The people there know what they are doing, and that includes the people who design covers, as well as the bosses of the people who design the covers.