So, this does raise an interesting point, especially in the age of games constantly evolving over their lifespan. It's something we've discussed internally about our reviews, as racing games are ripe for additions and modifications.
The thing is, for an initial review, we have to judge the product as it is, not as it might be down the road. Using GT Sport as an example, we can't say something like "car count will be 500" and mark it down as a positive, because a comment in an interview from a year ago suggests that might, at some point, happen. The FIA stuff is in a similar boat, although at least there's a set time visible on the horizon.
What's very strange, IMO, and could solve a lot of issues, is the Polyphony Digital Championship. That starts a few days after the FIA (tester) events. As a long-form event, I think it would've been ideal to have it ready to go at launch, when people are at their most impressionable. As is, the Sport Mode just isn't a massive step-change: it's three races quick races, at the same tracks for a week. I understand the rental cars in the Gr.4 and Gr.3 races — some players might not have them yet — but I think more variety in the current offerings would help. As is, it's an oval, and two sub-minute tracks, and all races are done in about five minutes.
Anywho, the main point I was going to make with this post is that the initial review is only one step for us. For the bigger games, that do update regularly (GT Sport, PCARS2, FM7), we want to take a look back at them at regular time intervals to determine how they've evolved. They probably won't be as thorough as our actual reviews, but we think it's important to document the changes.