Personally I think the half-plate armours are great designs for breastplates
Breastplates are probably my favourite armour from an aestethics viewpoint (especially the stereotypical wizard robe/long coat and breastplate looks) and to me the non-magical version look a bit too... fractured. I don't mind that so much for the magical versions because they can get away with being more "piecey" but I would like common breastplates to look more like they're a plate that goes over your breast.
I agree that some armours, like leather, could be bulkier. I also think hide should be bulky -- to me the difference between leather and hide is either using the skin of a thicker animal or more layering and fur. Magical hide (and leather) can be less bulky for obvious magical reasons.
I like very much that they've chosen to include the padded armour/gambeson look in all their armours. It's the foundation of every heavier armour, after all, and it delights the stickler for realism in me to see it.
Full Plate doesn't look platey enough. I think the upgraded Half-Plates look more like how a Full Plate should look. Which shouldn't be a surprise given that Half-Plate is supposed to be identical to Full-Plate except with many of the (half ) of the limb protection missing, as you mentioned. Once again the basic, unmagical armour itself looks more like what I could see magical Full-Plate looking like.
I too like the weapon design, including the morning star greatsword. Yes, I know it would be a really bad idea. But it would be a magnificently bad idea. It's ridiculous, but in a fun way.
However, last point. I'm not sure the linked pictures are the exhaustive list of armours. As far as I've seen there has been a few variants of all the armours in-game already, usually just details like shoulder pads or coat length, but still.