You would be able to see alright; your eyes would be right up next to the vision slit. It wouldn’t be great visibility but you could see enough to hit your opponent, which would be all that mattered. That helmet was made for a tournament; one made for a real battle would be of more practical design.
That’s nothing. Imagine being in an infantry line with this charging at you.
There are a lot of theories about why exactly the Hussars used those wings. Some believe it was for visual intimidation; others claim the feathers vibrated in the wind and produced a loud and ominous noise which would rattle the enemy’s courage. A lot of historians though believe they were just worn in parades and not actually in combat.
A Hussar was a great kind of troop because it managed to partially negate the big weakness of cavalry - their vulnerability to pikes - by giving the cavalry pikes of their own (lances). This was by no means a new tactic but the Polish cavalry were the only ones who continued to employ it into the 1600s and beyond, when all the other nations of Europe had abandoned the lancer. The lance would often be destroyed on the initial charge, in which case the Hussar would use his saber instead.
I’ve often speculated on what would have happened if gunpowder were never invented. The answer, I think, is that the heavy-lancer (abandoned at the end of the 1500s for the most part) would have been developed even further. You would have seen horses that were armoured as well as their riders. There would have been suits of full plate for horses that were articulated and reinforced as intricately as those for men. There would have been long pole-axes with blunt hammers at one end to crush the armour and create concussive force. There would also have been gigantic catapults and trebuchets that hurled enormous stones.
Well, crossbow would have been developed even further.
Yes. Crossbow bolts could pierce plate armour, and there would have been extremely powerful crossbows developed with crazy draw-weights and super-heavy bolts - maybe tipped not with pointed ends, but with blunted noses designed to produce concussive force. And, naturally, there would also be armour that was made even heavier and thicker to withstand these crossbow bolts. There would also be specialized physical conditioning programs for the soldiers who would wear this kind of harness, making them strong enough to carry its weight more easily.
Trebuchets and catapults would be designed to fling huge bags of iron spheres, which would tear open mid-flight and rain their contents onto the enemy.
The very obvious problem with that being that such armour (including those from the Greenwich Armouries) was usually coloured using processes which involved the metal being re-heated. Something no sane curator would ever countenance.
True, other methods are now available. But those would amount to just the sort of heavy-handed, interventionist fakery most museum curators now prefer to avoid. Better that an object is honestly presented as one with a history of its own than as spuriously authentic.
It was clearly because it looked fucking cool.
A mate of mine, who was incidentally the BBC man in Poland for a while, once described the Winged Hussars as the closest thing to elves that human history has produced. I kind of get his point.
Elves? The Hussars are way cooler than elves. I don’t think there are any fantasy warriors who even come close to looking as cool as what some real historical characters actually looked like.
My “I can’t believe someone wore it” moment was in looking at Henry VIII’s armour in the Tower of London - with its hilariously outsized codpiece.
Looked like it was designed by Blackadder. 
Of course, that wasn’t to show that Henry weilded the mightiest scepter of them all; but because the poor guy’s junk was permanently inflamed from VD.
Napoleon had the same problem, but codpieces were long since out of style, so he wore a custom special leather jockstrap held up by suspenders. The artist Jean-Louis-Ernest Meissonier was such a Napoleon-fanatic that he wore one to get the feel of it so that his painings of Napoleon would be accurate. (note the grim look on NB’s face in the linked painting.)
Speaking of “I can’t believe they wore that into battle” as well as big weiners, how about the Chalcidian helmet?
Henry might have had the thickness but Ferdinand, Holy Roman Emperor had more astonishing curvature.
