Because bottom line is, 3rd party along with all publishers want 1 and only 1 thing in mind, TO MAKE MONEY.
Why would you not put your game on a console if profit is possible.
Many gamer's may never agree to it but fact is, Nintendo made a console that is not future proof.
The Wii was outdated, as is the Wii-U spec wise, and Nintendo may have sold a shit ton of Wii's, but most 3rd party games either sold like crap, or were not even able to be released on the Wii ( AGAIN WEAK HARDWARE ).
2 Things needs to happen.
(1) Nintendo Needs to stop thinking that developers need them and realize that THEY need the developers
(2) Nintendo faithfuls need to let Nintendo know how they feel by speaking with their WALLETS.......







