Last rebuttal and I'll stop. Getting off track and all.
jgbrowning said:
I'll restrain my comments to things I know about.
The above is a logical fallicy. Just because something wasn't adopted doesn't mean it wasn't better. History teaches us nothing but that change takes time, tradition is often more important than reality, and other factors besides utilitarianism determine if something which is functionally better is adopted by a particular culture.
Agreed, but warfare/killing tends to be the top motivation for advancement of all kinds. Look to tactics used at Himagi Castle (butchered spelling). Trees that do not burn (or don't burn easily); grasses that when wet become slick, forcing enemy troops into a kill zone. Blood from arrow wounds makes for a great lubricant

. Hidden entrances and floors. It still stands because of a change in tactics: they covered the castle with black fabric when bombers approached during WWII. While culture and tradition may have stunted advancement, I don't believe that a definite advantage would have been ignored unless there was an overriding penalty. As you've said, we have no way of knowing with the resources of this site.
Look at climate charts. Most of Japan's rain comes between June and September. Here's a brief rundown
http://www.japaneselifestyle.com.au/japan/japan_climate.htm
Based my original comment more on experience. Can't say much against this.
In general European winter is brutal, not more conductive to combat. In fact the "war season" during the middle ages was traditionally after planting and before harvesting. Manpower availablity and logistics dictated such. Look up Medieval Warfare in the Wiki for a good rundown.
This condusive conditions were relative to each other. One includes fighting on frozen ground while dealing with frostbite and other conditions. Japan dealt with this as well as wet conditions (trench foot, disease in water or water based insects, etc).
Japan is much, much more mountainous on average than Europe. Look at a relief map. Here's a japan sample from a calander
http://www.trust-system.co.jp/calendar2005.jpg and here's a map of europe
http://www.freeworldmaps.net/europe/eu.gif. Europe has plains that are almost the size of Japan.
I'd wager this is due to Japan's significantly reduced land mass, by comparison. A volcanic chain will be nearly all mountain. But if I remember correctly (I could be wrong here, apparently the norm

) the Japanese had combat sites were largely within reach of the various factions by virtue of the country's size. As you mentioned, Europe had vastly more area. That meant crossing larger areas to reach battle areas, quite possibly during inhospitable winter seasons.
And even though I think you've got almost everything else wrong, I agree. The advantage of the current armor construction was that it was more bearable given the average summer warfare temperatures.
Why didn't the Japanese adopt metal armor more? That's a dissertation level question, but it's surely composed of availablity, quality, history, culture, infrastructure, and experience.
joe b.
Maybe I'm wrong, but this is what I've observed/read/theorized. There is agreement on this, including a cultural anthropolgist whose focus has been on the evolution of weapons and combat technologies (currently going for his masters degree). I can't be completely off-base.
Happy gaming.
