Is a Samurai Just a Fighter in Funny Armor?

This past weekend I posted about how I might approach an "oriental adventures" rules supplement, essentially saying that, where the OA book published by TSR was jargon-heavy and skewed more historical (and was heavily weighted towards Japan), I would skew mine more towards Samurai and Kung-Fu movies, and would try to make it more accessible to an English-speaking audience with a limited knowledge of historical Japan and China (and that I would balance it more between the two cultures).

The post generated a lot of good discussion and links, but regular GG commenter (and player in my campaign) Hamlet made the following observation (quoted here in part; go to the original to see the whole thing):

"...all you really need is a pamphlet covering the basics. A glossary of terms, a few pages describing culture and honor and the like, which can be done for Japanese, Chinese, Indian, assorted "other" cultures of the region...

"...for the most part, you have everything you need to run a campaign of samurai and ninja already in the core books. The PHB only needs a very light reskinning, which can be done in a matter of a few pages, to fit the bill. Fighters are now called Samurai or Bushi or whatever. Ninja would probably be thieves or multi-classed if demi-humans"

I found this a very interesting approach, and wanted to highlight it as a counterpoint to my original post. Is a new class beyond fighter (or cavalier) really needed to play a samurai, busei, or kensai? Or can you do it with just a new list of armor and weapons? What's a wu jen other than a mage with a different list of spells? Do ninjas need to be a class of their own, or, as Hamlet posits, can you just use the existing 1E thief (or perhaps assassin) class, wear a mask and hood, take a proficiency in shuriken, and be done with it? And do you really need an honor mechanic?

Any thoughts?