The bike riding side of me says ... hell yes - that complaint (about folding helmets) actually has some grounding in reality. I wear a flip-front (aka "system" or "jet") helmet for the great extra convenience and comfort I get out of it. However, that ONE point of articulation/single clip has measured disbenefits in cost, weight, protection level (only has to survive one major blunt-trauma hit, after which you junk it, rather than loads of bullets - but it's still less effective even for that), sealing quality and noise, and can of course fail (coming apart at the joint or the clip, etc). Mine is quite well made, so it's no worse than an everyday one-piece lid at half the price, but if the same level of tech and build quality was applied to a one-piece as to this you'd have a VERY nice helmet. (strong, light, etc)
Plus of course most of the protection comes from the thick layer of toughened polystyrene foam that it's lined with. Good luck making THAT fold up or slide smoothly in multiple layers.
However that side also wants someone to go all Tony Stark and make a fold-up one, as the weight isn't really so much of an issue (about 1.5kg) - but the bulk can be. Particularly when trying to attach it to my bike's pathetic helmet lock. Be so much easier if it could just pack up tight and go in one of the cubbyholes behind the engine along with the toolkit and manual.
The movie-watching/gaming side of me says ... dude, he's got a miniature fusion reactor (zero point generator? something else? i dunno. wasn't paying attention. isn't important) that chucks out a couple hundred kilowatts IN HIS CHEST and doesn't suffer any effects from heat and radiation, has made some kind of electrically powered impulse engine-cum-photon torpedo thing that fits in his hand, and built the first version of both the generator and his power armour in a desert cave from scrap metal. The dude is both a genius, and clearly operating under cartoon physics. He's got license to make stuff like that.
(BTW thinking of cartoon stuff, I'd like to put the blame squarely on Michael Bay for starting all this when he changed the transformers from sheet metal to chaotic piles of shrapnel)
Now, story universes where they're trying to impose some measure of reality on the situation, that can't fly - your character SHOULD be hobbled by having to deal with a bulky, fixed-size/shape helmet (maaaaaaaybe with a "jet" option, given that the name comes from fighter pilots using them). Save the folding awesomeness/silliness for the more outlandish ones.