The problem is they do careful analysis of statues and find evidence of pigmentation, but obviously they're only looking at the remnants of the base coat and don't see any of the careful detailing that almost certainly went towards making these statues look very lifelike (judging by the realistic quality of the sculpture itself.) And so the recreations look flat and uncanny because they're essentially unfinished.
The bright clothes are fine, but his skin is awful. It's flat and lifeless, like a cold corpse drained of blood. It looks like they put the primer coat on then left it unfinished; I think that's literally what they did. Maybe this look is what they were originally going for, but I don't think so. Look at the detail on that guy's knees, they look just like real knees. I don't believe the original artists went through so much trouble to sculpt hyper-realistic knees then let some intern half-ass the paint job.
I think it's also current museum aesthetics where they do enough to give you the idea but don't want to take any artistic license beyond what's provable. So the painting could have been more subtle especially for those close to the viewer
