While this isn't normally a problem for commercial sites like FSM, there is a lot of pressure to get the "in box preview" done quickly. Normally, the kit is sent to a site and the owner of that site sends out the kit to volunteers to do a review.
The company wants to see reviews of their kits on the web as soon as possible. Then you have to temper the review, being honest (if it's bad) with being grateful to the company who sent you the free kit. You won't survive if you constantly "bite the hand that feeds you" by writing terrible or tardy reviews.
Conversely, if you constantly heap loads of praise on mediocre kits, you run the risk of becoming a shill for that company. Then your reviews are worthless because no one will read them because they know that company could toss empty sprues in a box and you'll write how great the kit is.
Then there's the whole "subject matter expert" matter. Having spent a good number of years on a website's review corps, the review is often only as good as the reviewer's knowledge. On a website I used to review for, I was offered the new (at the time) Dragon M1A2SEP to review. My personal experience on the Abrams line ended at the straight M1A2, and I wasn't as familiar with the SEP as I felt I needed to do a quality review of such a nice kit. There were just too minute detail changes between the mid-90s A2 and the post OIF SEP.
All those little changes (I knew the obvious big differences) really mattered to someone wanting to build the most up-to-date, state-of-the-art, definitive Abrams model kit to hit the shelves in 25 years. I know I couldn't wait to get one, but didn't want to mess up a review on such an outstanding kit that was probably the most accurate modern armor model available in plastic.
I passed on the kit, suggesting they give it to someone more qualified to review the kit for its accuracy. I mean, anyone can tell you what's in the box, how the parts look or if all the iddy bitty pieces fit together.
Instead, they gave it to someone who didn't know any of the variations of Abrams tanks over the last three decades and they wrote maybe a dozen sentences about the kit. It was disheartening to see a long awaited subject be treated to such a hackneyed review.
Believe me, I've been sent models to review that I had very little knowledge about and had no interest in the subject matter. Then the review becomes tedious work. It's one of the reasons I no longer do reviews.
Another reason is the readers that criticize the reviews. If you don't like the reviews, volunteer to write one yourself. Grab a kit off your shelf and write a review of it. Submit it to any of the non-commercial modeling websites; they are always looking for new reviewers. Even multiple reviews on the same subject are welcomed. It is always better to get a look at the kit from a different perspective. Perhaps one knows more about the subject, but you build better than that person or vice versa.
Or maybe someone did the dreaded "in box preview" or added all the bells & whistles and now you can do a full up OOB build review.
Don't get me wrong, everyone has a right to complain, but if you don't like the way reviews are done, do them yourself. [yeah, yeah, I've heard the excuses; no time, can't write, dog ate my homework, etc.]
BTW Hans, Military Model Preview (search for that model magazine on eBay) used to do reviews of armor and aircraft kits built OOB without painting them and decals on bare plastic. They were often overly harsh and stopped getting gratis kits to review from manufacturers. They did not last long.