We haven't seen him move yet, how do we know he won't be moving elegantly ? Muscle mass on a frickin' alien would mean he isn't capable of being fast and graceful ? Just because he's big ?
In defence of people not seeing this huge predator to be elegant, is simple, the basic design language, if you want to make a tank, he going to have huge chest, traps, biceps, legs, he will be very heavy and moving very heavy, if you want to make a agile elf, who moves very elegant you making him slender, light. That's simple design rules. The Upgrade does look more tanky then agile type. But then again you can break every rule if you know how to manipulate them, so I totally don't have no problems with a huge tank looking creature moving elegantly like a an elf
(don't take my words literally, just exaggeration).
But also I want to point out that the Upgrade doesn't look like he took too much steroids, I mean the proportions of his body to his height looks pretty good, I mean he looks like just somebody took Jungle, City hunter, and just up-scaled them. And added a little bit more muscles on arms. Yes his torso has more developed muscles then Jungle/City Hunter, but it's nowhere near as Powerlifters from AVP 2004.