I think especially us older gamers have been burnt so often in the past, that we've become a rather suspicious bunch of people. We've all held high hopes for a game in the past, only to see those hopes terribly disappointed on release day. When I look at the footage and videos of Jurassic World: Evolution I think "Damn, this looks so amazing.", but at the same time, there's this nagging voice in the back of my head that says "Careful, it might become the next big disappointment." That's why I haven't pre-ordered the game yet and why I hope Frontier releases another (more final) gameplay video before release. It always boils down to the usual pre-release "hope vs fear"
Let me exemplify this with the AI discussion:
If the Dinosaur AI is only half as impressive as the Dinosaur animations and their models, then there's nothing to worry about. The attention to little details in animation and color schemes still blows my mind away. Since the Dinosaurs are clearly the main attraction of the game and the Devs have spent a great deal of time to make those Dinosaurs the best looking Dinos in
any game so far, I have high hopes that the animal AI received the same level of attention. But as a matter of fact: We simply don't know much about the final game AI yet. Animal behavior in the earlier (gameplay) builds looked somewhat "static" (e.g. the groupings of three Struthiomimus who face each other and then talk about the weather or about whatever Struthi wasn't in the group at the moment). Then again, trailers of the game clearly show groups of herbivores moving together through the paddocks in herdes.
We've also seen gameplay videos in which a large carnivore attacked a Triceratops, while a second Triceratops just stood around, minding its own business. It would be somewhat disappointing if the animals were artificially locked into "1vs1" duels, despite scientific evidence that at least some would actually cooperate to defend themselves from predators. For all we know, Triceratops would form defensive formations to fend off the attacker (there's an example from JP Lore in the Lost Worlds novel, when a herd of Triceratops formed a defensive ring to fend off the attack of a pack of Velociraptors).
The scenes of herbivores fleeing from attacking carnivores (most famously the Triceratops running from the Raptors or the scene from the Spinosaurus dossier) could be fully functional game AI, but also simply scripted animations for the trailers. Until we see this behavior taking place in actual gameplay footage, we simply don't know the truth. Again: hope vs fear
"Cosmetics":
Another aspect that's frequently mentioned is the perceived lack of "cosmetics" like trash bins or banks. I wouldn't degrade those items to a purely "cosmetic" status (as in they do not effect the rating of your park in any way, shape or form). On the contrary, I'd argue that those details should have impact on your park rating and the overall satisfaction of your visitors. Having a nice little picnic spot next to a Sauropod enclosure or a scenic route with benches, hedges and stationary binoculars around the T-Rex paddock should make your little visitors happy and increase park rating. At the moment, the construction part of the game looks a bit bare bones to me. Therefor, such items should be part of the initial game release or at least should be added in a later patch (if the fixed release date is an issue). Additional items and/or collections of items can still be sold via DLCs at a later time.
To conclude, I do not think that voicing concerns is equal to being "overly negative of the game". Constructive feedback is vital for improvement and to iron out possible design flaws before they can become an issue in the final release. As we have seen, Frontier took some of the feedback from testers in the first gameplay video to the heart and showed an improved version of the game in the latest IGN gameplay video. Therefor I hope they also read and listen to concerns about AI, "cosmetics" and the immortal (Power

) Rangers and either address it in a Dev Diary or a new gameplay video.