BTW, I tried to do a quick google on the current research and mostly came up with mixed answers. If anyone form HN knows about dino feather coverings, please chime in!
The perception of realism would still matter.
Just use test audiences to see what people believe looks the most real.
Also, a realistic T-Rex may never survive in our modern atmosphere. Those lungs are so large because O2 content was about half of today's (http://www.firstpost.com/tech/news-analysis/atmospheric-oxyg...) and the mix of dinos they have in JP is just a mess of evolutionary reality.
Trying to say that the dinos are realistic is just crazy. Maybe, kinda, in the first one, they were, a little bit. Even then Jack Horner got a lot of flak from the community over his consultation on the films. But the evidence we have now just points to a much different creature than what we though of even a few years ago. They aren't monsters, just standard terrestrial vertebrates trying to make their way in a different world. We have so much to learn from them, about climate change, about physiology, about adaptation, etc. So trying to keep the monster and the known 'reality' separate is a big deal to me.
Then let's go for plaid and gingham dinosaurs, like the pink elephants on parade!
It doesn't need to match reality, it needs to aid suspension of disbelief. If color choices make the audience say, "That looks so fake", it hurts the storytelling.