I don't understand why you think "Japan" is responsible for this. As far as I can see there are two reasons:
1) The lack of interest from western publishers. The (classic) Wizardry style of RPGs was largely considered outdated in the west (especially in North-America) by the time the first Japanese Wizardrys started popping up. And as far as I know none of the Japanese Wizardy developers had their own publishing-branches in the West (except Atlus, who did put out one of their two Wizardry games in the west) and thus couldn't publish them in the West even if they had wanted to do so in a market that largely seemed uninterested.
2) Copyright problems. First off: the copyright belonged to Sir-Tech in the west, so if they weren't interested in either publishing the games themselves, or in extending their license to someone else, the game wasn't going to get published at all. Furthermore during the production of Wiz7 Sir-Tech entered a large legal dispute over Wizardry, which at times made it illegal even for them to publish Wizardry games. For example they had to move to Canada to be able to get Wiz8 out, and even then they got in trouble over it. By the time this was cleared up Japanese Wizardry development was entering a hiatus that it didn't get out of until the "Wizardry Renaissance" line that started in 2009 (and included the Wizardry games for PS3 and Wizardry Online both of which did reach the west).
dtgreene: I should probably point out that you will want/need to play Wizardry 1 before Wizardry 2-4.
Wizardry 2 expects you to transfer high level (13+) characters from Wizardry 1.
Wizardry 3 requires you to transfer characters, but their level doesn't matter since it will be reduced to 1.
Wizardry 4, which is not like the rest of the series, expects you to know some things that a newcomer would not know. (It's also not what I would call easy.)
If I'm not mistaken only the original Apple version of Wiz2 absolutely required you to transfer characters. And I think even the Apple version of Wiz3 allow you to create new characters if you didn't have any to transfer.
Sarisio: Basically Elminage Gothic stands as one of latest Wizardry iterations. It has all Wizardry classes and races, much better graphics, tons and tons of content. It doesn't have any voice-acting however.
Elminage are Wizardry games in everything but name. Their developer Starfish used to be one of the most prolific of the Japanese Wizardry developers (mainly through their Wizardry Empire series which lasted so long that the last game even made it to the PSP). When they lost the license they just kept doing the same thing under the Elminage moniker.
This is actually quite common as far as this franchise is concerned. Some of ASCII's
Wizardry Gaiden games were ported to Japanese mobiles under the title
Netherdomain. Michaelsoft's (weird and somewhat silly)
Wizardry Xth 2 was renamed
Class of Heroes (and visually retooled to be even weirder and sillier) when it was ported to PSP. This port even made it to the west and have at-least one sequel of it's own. D.W. Bradley's (the main developer of WIz5-7)
Wizards & Warriors is by some considered something of an alternative Wizardry 8 and is often assumed to contain a lot of the ideas he had for that game. And then there is
Grimoire: Heralds of the Winged Exemplar ...which it seems to be bad luck just to talk about at length; so I won't.