Starting with the most popular game in the franchise OoT.
It sold 4.1m in North America, the N64 sold 20.11m giving it an attach rate of 20%
In japan it sold 1.45 on the N64 which sold 5.54 giving it an attach rate of 26%
Next is Twilight Princess on Wii
NA-3.66/45.18=8%
JP-0.6/12.76=4%
Trying to stick with recent games as they are more relevant, Spirit Tracks attach rates are 2% for NA and Japan
Skyward Sword was 4% for NA and 2% for Japan
Anyway as you can see its really not that bad, try comparing it to some many other franchises. The older games in the series were indeed more popular than the newer ones in Japan though.
I would also like to point out if you are going to look at raw sales numbers you must first look at this
1,014.10 this is the number in millions of the top 200 selling games in NA combined. Lets compare that to Japans, 431.29
Simply put, games sell more in NA where they have a larger population.
