I would posit that later period armors, especially the highly detailed/decorated ones such as we might see in the museum were likely parade or tournament pieces...meant to be worn at the event and then retired. I bet the field armor, which would've been plainer, more utilitarian, was probably stouter given its function. Just my opinion; as I've never handled either I can only speculate and bow to my more-informed brethren.
You all remember the article about the bones of a knight found in the lower part of the ruins of what used to be a castle; in their examination of the bones they noted that the man was likely around 5'7", heavily muscled and his joints showed signs of wear that were consistent w/being in armor and engaging in battle. I don't have all the particulars, but it is in a thread on here somewhere. Of course, that is just one case but it did make sense to me...
One can't help but become stronger, more muscular if you're constantly encased in 50lbs of steel, leather and clothing, riding, walking, eating, sitting, etc.
I wonder if I could get away with wearing mail to work, daily. lol