I think the mistake here is assuming that Nintendo's business model and aspirations can and should be anything like Sony or MS.
Nintendo's fortunes with any given system are largely tied to how many consoles they can sell. The more consoles they sell, the larger user base they have to sell their extraordinarily popular franchises to, the more money they can make. Certainly they can make money from third party licensing fees but that is much less than what they make from their own games and in effect third parties are competition with their own titles. Other ways Nintendo can improve the bottom line is by spending less money on R+D, selling hardware at a profit and being efficient (frugal) with game production. These are things that Nintendo has historically been very good at and why the profit they earn (even in their lean years) is very high in relation to their number of employees. Remember Nintendo is only just over half the size of EA.
So with that said I think it is a mistake to assume (at least in this reality) that 3rd parties are a very significant part of the equation for Nintendo. Nintendo's primary driver is profit, not winning console generations, winning is just a means to an end. If they have good profit but only sell half the console numbers of the competition, they don't really care, for Nintendo that's a win. Selling a hundred million consoles doesn't necessarily mean anything to them because the amount of profit they might earn from third party licenses still wouldn't be enough to offset the losses/gains they can earn by simply having their own business in order i.e. efficient, low cost operations with an affordable product.
For third parties they equation is simpler, by far the biggest modifiable for them is (any) userbase, more userbase gives more potential sales and profit. They have fewer avenues to address profit than Nintendo does as both a software and hardware vendor. There ideal situation for third parties hardware-wise is a single successful platform, so they can effectively make one game and sell to 100% of the userbase. PS2 (and PS1) was the closest and to this and is part of the reason why Sony has such a good relationship with third parties, EA and Ubisoft etc. would love to see another PS2-like success as it allows them to focus resources on a (almost) single target.
For them (third parties) to be an important part of the equation from Nintendo's perspective you literally need third party games driving sales of Nintendo systems above the rate that the system would be purchased if /mostly just Nintendo games were available (pretty much the current situation). This would require, at least, complete third party parity. If third parties are attracting a larger market to the console, that is good for Nintendo as it improves the install base and allows them to make significant money on licensing and sell more of their own games.
We are so very very far from this situation now that I just don't ever see it happening, such a strong historical trend has been established I don't know how it will be broken. I think Nintendo is now begninng to think the same, but it's taken them a long time to reach the necessary level of realisation. Nintendo can throw money at third parties all they like to improve the situation somewhat, but they can't get them all on board this way, it simply isn't cost efficient. From Nintendo's perspective and the reasons highlighted above that money would be far better spent internally bolstering development, improviing efficiency etc. which is I think where Nintendo is currently focusing attention. They have much work to do in improving their output if they want to thrive on this approach and not the moderate Nintendo output/moderate third party output that has worked in the past.
Where does that leave the poor consumer? It leaves them having to buy multiple consoles if they want to get all games, but that situation would still be the same even if Nintendo managed to get half the major third party games on board, a still lofty goal from where they presently are.
MS and Sony are in a bigger fight than Nintendo and have been willing to throw money at the problem for longer term gains by, for example, spending more money on hardware R+D, loss leading, paying for exclusives etc. They can to a greater extent rely on the fickle third parties because at the end of the day it is only a small part of their business and if the third parties let them down they have other businesses to fall back on. They can rely on a fundamentally different approach because they have fundamentally different drivers and have the ability/desire to take different risks from what Nintendo can.
I'll stop there.
