And that means...what exactly?! I'm sorry, but your body shape isn't the only one in the whole wide world. Body shape depends on several factors. Activity, diet, gender, age, race...and genes. That last part is the end all to all "It's unrealistic because it's not like me" arguments.
Or are you telling me that
this photo is actually a drawing of our Hyur? What about
this and
this?! Realistic means "possible in nature", not "common in nature". A 2,7m high human is realistic...but there was only ever ONE such human in known history, so don't expect to ever meet one. In fact, the tenth highest is "only" 2,46m, so there's not much you will meet of anywhere near that...
It's like some woman saying that if she have small breasts even when overweight then it's unrealistic for a person to have large breasts, let alone slim one. And to see how wrong that is all you need to do is spend 10 minutes outside in a crowded place. Genes decide where fat is distributed and in what quantity. It happens very rarely, but in some cases, buttocks are very low on the priority list and won't receive any fat until the person will be outright obese. And you can talk about the characters being fit all you want, but the fact of the matter is that the other tissue on top of muscles and fat on the leg can form a flat butt even for a person with them pretty finely tuned. There are countless people with surprising strength where you wouldn't say they are anything like that, looking even a bit "fat". That's because humans anatomy is not a one-size-fits-them-all. There are myriads of possibilities thanks to a multitude of factors.