Comics and animated media in Halo are like... the most inaccurate things... In comics armor looked very often disfigured and disproportionate. Same with the Legends. Sometimes it was really painful to look at, imo.
Well, all I can say is that if Halo was done by Japaneese peeps you'd surely have had it looking way different - huge pauldrons, etc.
I personally didn't see anyone building a suit like that - Halo suits are more practical. You don't want a huge World of Warcraft-like shoulder pauldrons, they are totally unpractical. ODST armor is actually practical and it was designed so that we - audience should buy it.
It doesn't matter how tall you are and your body type. You make armor to fit you.
FANGS wrote it great in the "Deployment" thread - you make the armor fit you, that people buy it that it's armor you wear and not that someone borrowed you. Fit. Fit. Fit. If you have more muscle, like you did, you have to enlarge it. You make the armor fit you.
It's easier with slimmer people - you can either cut the piece to fit or you can fill it. If you want to portray a very lean and no-muscle rookie, you can, if you want however a more hardened ODST that gained muscle through training - you can do it even with a very lean body. You just add mass - foam, other materials and it'll give the appearance a person wants. ODST are wearing full body suit and armor - they aren't naked so you can make a lot.
If someone has more mass - they also make the armor fit them. If it means to enlarge some parts, they do it. People do wonders.
Make the armor fit you, that's the most important thing.
Even people at 501st or ones who want to join them and buy the Anovos Stromtrooper kits - they have a lot to do to make these kits fit their body perfectly and their bodies vary a lot, yet the Stormtrooper armor is pretty generic - no oversize parts, etc.
...unless you are aiming for the oversized comic/anime thing, of course.