Yes, definitely one thing the game needs is more realistic animals, in terms of both appearance and animations...
As for what JPOG did better, well, lot's of things... animal posture was much better, particularly in bipeds; they feature a proper horizontal back and tail balanced evenly at the pelvis, deviating from a horizontal stance only to feed, get a better view of their surroundings, be intimidating or any other special action. In JWE the posture of the bipeds are all over the place; some animals lean back as if their tails are too heavy or lean forward as if their heads weigh more. And of course the hadrosaurs are much better animated; all walk with a proper quadruped stance... and when they run they all move on two legs (including Ouranosaurus), maintaining a perfect horizontal stance with their arms at a proper position held against their sides.
And then there's the running animations... let's talk about all those problems. For starters, animals run way too much in JWE... typically animals don't run unless they are doing something that requires running, like hunting, escaping, playing and so on... which in JPOG was usually the case; the animals didn't run while wandering aimlessly, they walked, only running when the activity dictated it a necessity. In JWE animals will run for just about everything, from closing the distance between them and a food dispenser to just wandering their pen... a fact that makes the general running animations all the more ugly. Again, it's largely the bipeds that are at fault, and having addressed the hadrosaurs above I'll skip to the obligate bipeds; theropods, dryosaurs and pachycephalosaurs. For one, their tails are often too narrow and they whip around freely and often erratically, which not only looks bad but doesn't make for a convincing counterbalance... JPOG on the other hand gave the dinosaurs thick tails that, while not completely inflexible, featured a much more restricted range of movement, largely limited to minor left and right swinging, which is what one would expect for a proper counterbalance. For another, just compare the theropod running animations of JPOG to those in JWE... it's not really running at all, more like a swift walking, which again it what one would expect from a large biped with a very high center of gravity and somewhat delicate balance. Then there's the fact that the dinosaurs can turn while running in JPOG... in JWE they can only stop, turn, then start running again... kind of like a Sims character (speaking of The Sims, the way dinosaurs gather in circles to "talk" to each other... weird). And lastly... stopping... running dinosaurs in JPOG slow to a walk before stopping... in JWE they all go from running to an abrupt stop with this cartoonish animations that looks super awkward and super unrealistic.
Another nice thing about JPOG is that they weren't afraid to deviate from canon dinosaur design to give them a more realistic looks; the Pachycephalosaurus had a proper horizontal stance as oppose to the hunched one seen in JWE, the Ankylosaurus had a wide mouth, short legs and a flat body as oppose to the narrow beak, long legs and curved hump and drooping tail seen in JWE, the Ceratosaurus is more accurately scaled (it's not even big enough to swallow a goat, let alone a human). Oddly enough JWE often deviates from canon appearances as well, but instead of making them look more realistic they just make them look weirder...
It was also nice how combat in JPOG was largely handled in real-time with carnivores chasing prey and only nabbing them if their head came close enough to grab the target. To be fair, combat between larger animals was pretty dumb... any hit would cause a large animal to flop over and when it came to herbivores they had a habit of running aimlessly, flailing their heads or tails at random with no obvious strategy or target.
Found a nice little Youtube video
right here depicting the various dinosaurs in JPOG... it's not perfect (only the carnivores run and that's because they're hunting) but it gives a basic idea of some of the game's animations.