Well, the global install base for the 3DS is 58.2 million, which is quite impressive. Maybe most everyone who really wanted one has already bought one and is happy with their current model. I personally never saw any reason to "upgrade" to the New 3DS XL. I toyed around with one that belongs to a friend of mine and felt it was inferior. The C-Stick is worthless, in my opinion. Memory is a pain in the butt to get to. The top half of the system is really wobbly and slides from left to right on its hinges a little too much for my taste and made it feel somewhat cheaply made. The faster processing is a plus but it really wasn't noticeable to the point that it was a game changer for me. And, to my knowledge, the only exclusive game for it is Xenoblade, which is a vastly inferior port. Nobody in their right mind should play that version if they own a Wii or WiiU. Then there's the whole fiasco of Nintendo deciding not to include a charger with it :/
I'd imagine a lot of core gamers who keep up with industry news and whatnot (who don't own a 3DS) are probably waiting to see what the NX is actually going to do on the portable gaming front, too, before buying a 3DS.
P.S. - I also have Yo-Kai Watch on my to-buy list.