Most typical Nintendo players I know do not like playing first person games. Japan gamers are notoriously not into first person games much.
When Metroid Prime came out, it was a novelty that was featured heavily in magazines and obviously it reviewed very well. A lot of people gave it a try. But the drop in sales with Prime2 and only a mild recovery with Prime3 on a 100+ million console, tells me that a lot of typical Nintendo players could not gel with the first party gameplay.
The Prime fandom is there, but isn't very large. The mildly disappointing sales of Prime remastered is another reason I believe Prime4 will not be the huge seller that people think. Perhaps somewhere around 2 million.