TL;DR: We use the author tags when there are few questions per work and in total as current practice already, this should be incorporated into current policy.
Current policy would appear that author tags are to be used solely on questions about the authors themselves and not for questions about their works.
If the question is asking about a) aspects of the author's life, or b) aspects of the author's work that are not specific to a single work or franchise, then we tag the question with the name of the author.
What is the correct usage of individual works tags vs. author tags vs. franchise tags?
This meta post also quotes the same thing above and uses that to come to its conclusions.
This post about Fahrenheit 451 and Ray Bradbury has no clear consensus but does point to how things are done in practice.
This comment alludes to how things are done in practice.
Re: "author" tags... imho, the utility varies greatly depending on how many different titles the author contributes. For example, J.K. Rowling only has the Harry Potter world (at least as far as relates to SciFi/Fantasy), but authors like Heinlein, Dick, etc., have dozens and dozens of titles, many of which only have the author as a common factor. I see utility in have author tags for the more prolific writers. I might want to look through the Heinlein tag for ideas for other books of his to read, for example. – Beofett
In reality though things are currently slightly different: we use the author tags when there are few questions per work and in total. However, if there are main franchise/universe tags we should still be using them in place of the author tags.
Of course there is no explicit cut off on when we should stop adding author tags to works with higher than "few" questions so we use common sense.
What needs to be done?
Current practice should be incorporated into current policy.
Apart from that personally I don't think anything needs to be done. The author tags are already used in the proposed manner in cases where it is more appropriate and do we really want to group works by tag just because they have the same author? I don't think so. If the work is unrelated to another work in universe then they don't really need to be linked.
So how can you follow them easily?
Well depends on the author and the traffic they bring to the site. I believe Ray Bradbury and Jules Verne already have their author tags used as "all works by author" so not a problem there. Though I'm not too familiar to check all the works to see if this is the case.
In cases where the author tags are used solely for questions about the author well then there's generally quite a few questions already. To take the below example adding the author tag wouldn't make it easier to find new questions about Wild Cards, The Thousand Worlds or whatever other work he's letting distract him at the moment because they would be lost in the storm of Game of Thrones and A Song of Ice and Fire questions. (Note: adding the author tag to GoT questions wouldn't necessarily be the case but the point still stands even if it is solely applied to ASOIAF questions).
To take things to an extreme example lets look at George R. R. Martin. There are currently, that I'm aware of, 4 universe tags that relate to his works and the author tag:
In this case do we really want to have to retag 2,383 questions to have the author tags on them and then dilute questions about the author themselves. This would then also hold true for harry-potter, although slightly different because there's only really one work here.
On a side note this might not work as you expect. For example, if you watch ray-bradbury but ignore fahrenheit-451 questions tagged with both will still show up as highlighted. See this answer to the meta announcement, for example.