[kohsuke]

There's one word that I expected to be in the list but it isn't, which is もったいない (mottai nai)

It describes the situation where something/someone that is still of some use is left unused and wasted, such as leaving food on the table or wasting somebody's talent.

I'm a Japanese who's been living in the US for more than a decade, and I always thought this one word represents what's missing in American culture the most.

[mcphage]

That sounds like it's most equivalent to "squadered": http://www.merriam-webster.com/dictionary/squander