The easiest way to look at this is the rule of Nintendo: the more routine and obvious the solution, the greater the chance of Nintendo fucking it up. I'm amazed they figured out how to properly harness electricity to make their products work in the first place considering how conventional that idea is.
A big problem with owning Nintendo systems is that the crappy third party support makes for slim pickings. You can go months without a title interesting you being released. Of course if you bring this up with Nintendo they'll be all "what are you talking about? We released..." and then they'll list everything released in the last year. Of course they'll include games for both their console and handheld and online games and any sort of re-release or remake. Remember how all the NPC games came out in a blob during a time where the Wii had like no games for months and months? In Nintendo's mind those "counted" even though someone who already owns the Gamecube versions probably doesn't want to buy them again.
Other things Nintendo fails to realize:
-Not everyone owns both their handheld and console
-Not everyone is interested in buying old games
-Not everyone shops online
-Not everyone has the same tastes
Nintendo just lumps us all into a big group. That's why they sucked at releasing "mature" games. That's why they really don't seem to get this core gamer vs. non-gamer thing. That's why they don't really seem to understand why third party support matters. A good videogame system accomodates many tastes. So you'll have different titles that appear to different skill levels, different ages, different genders, interest in different genres, etc. Nintendo talks a lot about being an "everyone" console but there is no videogame company that outright sucks at that more than them.
They blob us all together and then come to the conclusions that if they're not careful the different products will eat into each others profits. That can happen but only when those products are all aimed at the same market. Xenoblade and Wii Fit DO NOT EAT INTO OTHER. The crossover market for that is limited to Nintendo fanboys. The two games are so different that a demographic that liked one would almost certainly dislike the other. They think if they release too many VC games that people won't buy new games, which is nuts. Not everyone likes the same stuff. You can't completely prevent games from eating into each other's sales but pleasing NO ONE by assuming every title has the same appeal to everyone is worse.