Market Satuation? niche in appeal?
Golden Sun is the only thing that should have sold better on that list, I think it just arrived at a time where the DS is dying software wise. It deserved a remaster on the 3DS or a collection re-release
Fire Emblem only blew up with the 3DS, prior to that it always had small sales.
World ends with you didn't have a huge budget (i dont think any DS games did lol), 700k was probably decent considering its a 2D sprite RPG and new IP with a strange battle system
Again other then Golden sun I think the games only performed poorly when compared to casual titles or Zelda/pokemon/Mario







