I don't write reviews. I've made a point of not calling anything I write on MoeGamer a "review" because that term has become extremely loaded and brings with it a whole mess of expectations and conventions that I don't feel are especially helpful. And I kind of wish that the broader Internet community would understand a few things: 1) not every piece of writing that is about a specific creative work is a "review", and 2) a review is not the only means of exploring a creative work, and in academic terms is probably one of the least desirable ways to do so.
What I say here of course hinges on your definition of what a "review" is, so here's mine. I'm going by what I grew up understanding a "review" to be, a piece of knowledge I primarily developed from games magazines, but which was also supported by magazines about other subjects (such as music and movies) and TV shows.
A review, to me, is a piece of writing (or otherwise "composed" form of media, such as a scripted audio or video clip) that, above all else, casts some form of judgement about its subject. In the case of gaming, a review is typically framed as a piece of buying advice: is this game worth you spending your money on?
The supporting evidence for the answer to that question can be technical (does this game work as intended?), artistic (is this game successful at exploring the themes it attempts to tackle?), completely personal (did the reviewer like it?) or, increasingly these days, sociopolitical (is this game inclusive/exclusionary?) but the end result is always the same: some form of judgement as to whether or not the work is "worth it", be "it" your time or your money, depending on the form the work takes.
The trouble with this question, and particularly attempting to quantify an answer to it, is that everyone's tastes are different. If you say "no, this is not worth buying", then there will be someone out there who disagrees — someone who did buy it, thinks that it was worth buying, and consequently finds the review less than useful as a result. I say this with confidence as I am typically that someone.
There's an argument to be made, of course, that if they've already bought the thing they don't "need" the review, and this is sort of what I'm getting at. A review, by my definition, typically assumes people are reading it from a position of not owning the thing and perhaps being completely unfamiliar with the thing. What about those people who do own the thing and who are already familiar with it, and want to find out a bit more about it? What do they get?
Not much, under the current model. Sure, you might get a few clickbait guides and news stories about whatever the big game of the day is in order to maximise those SEO hits, but in terms of more in-depth, serious analysis? Not a whole lot. And that, I think, is something we're sorely missing — writers aren't delivering it, and readers aren't demanding it.
You may well ask why writers should deliver it if readers aren't demanding it, but with anything like this there's always the possibility that readers aren't demanding something because they don't know they want it. If you've never had something, you don't know you want it again, after all.
And it seems there are people who want this kind of thing. The things I post about games tend to be long after their original release and that initial desire for "buying advice", and come from the perspective of having played the game extremely thoroughly, preferably to full completion, Platinum Trophy or whatever. And, where possible, I avoid making subjective value judgements about whether the game is "good" or "bad", because I've seen more than enough examples over the years to know that my "good" is not necessarily the same as your "good", and vice versa.
There's also precedent in other media, too. Look at academic literary and film criticism. Typically speaking, an essay written about a work of literature does not conclude with something along the lines of "this was quite boring, 7/10" (even if it's Tristram Shandy, which is very boring — but deliberately so, which is part of its twisted, awful genius); likewise, a piece of academic writing about the history of film doesn't knock points off for the special effects from a 1960s movie being a bit janky compared to today's CG. It doesn't award "points" at all.
I'm not so grandiose and arrogant as to declare myself an academic scholar of video games or anything, but when I write something I do make a point of trying to both contemplate the work from a "timeless" perspective, and likewise write something that will remain timeless. I have articles that I'd be more than happy to show people in 20 years' time that talk about some of the games I think are interesting and/or are of historical significance; contrast that with anyone who, say, contributed to the original Nier's 67 rating on Metacritic, all of whom now look extremely foolish given the widespread appreciation and understanding of that series and its creator.
Let's see more writing about games; less writing about whether or not you should buy games.