I'd be willing to bet a lot of the people who complain most loudly about this didn't bother to support Wii U third party games themselves.

I have COD: Black Ops 2, Assassin's Creed IV, FIFA (via eShop), Batman: Arkham Origins, Tekken Tag Tournament, and Rayman. So I did my part. 

Because it is always a bad Pr in the end with Nintendo fans complaining about how much the Port suck. So no real benefit in doing it when they could use the time and money for something more profitable.

Selling a measly 300K on Wii U would actually be an improvment. CoD didn't even achieve that.

1.300k -500k is not profitable for larger western games. Perhaps in the 90's not now. AAA games (most of the time) need over a million in sales.

2. If what you said was true about people hating on Nintendo, third party would not be cutting the chord on last gen consoles either. They've been telling people they needed specs higher than what Nintendo offered since 2011 (or possibly earlier).

3. The Wii U is not far from the 360 and PS3 in specs capabilities.

In reality its just Nintendo doing what they've always done which is not listening.

A port from the not existing 360 version? I suppose it won't be cheap.

There ain't no Witcher 3 version which has to deal with a system with less than 5 GB available RAM. The Wii U has 1 GB RAM available for games, the rest is used by the OS.

1.They could potentially use that 1m/time on something that would make back more money or support the longterm growth of the franchise/series

2.They can't be bothered. If someone asked you to run a mile for $10 when you make $100, unless you really enjoy running you'll probably be like "Nah, I'm good.

Very true, I run a Wii U group on facebook and the numbers don't make any sense... a new copy of HYrule Warriors costs around 60 U$ with importers a copy of the better Deus Ex you can find it easily for just 20 U$, and guess which game is purchased constlantly and which one is not even looked at? Best part? most of the people in the group is a single console owner as in my country is very expensive to get 2 consoles so is not common.

Because they already tried and it failed, the Wii U is selling really poorly, and it's just not worth it. It's probably extra work too, with the gamepad and different hardware and all. : /

Even with low costs porting is a risk on the Wii U, and they don't want to take it... lets use an hipotesis that porting a game to the Wii U costs around 1 million to 3 million, just to RECOVER the costs they need to sell between 50.000 and 110.000 units AT FULL PRICE, which in the console is not always achievable, a game like Injustice: Gods among us is sitting at 140k units sold, most of which were NOT sold at full price, so that game was a loss for them.  Why take the risk then? just ignoring the console they could be saving money and that is what they are doing.

Now porting can be way more expensive if the engine is not available on the platform in the first place which is what happens with Konami, Square-Enix and new EA games.

If the BEST they can hope to sell on the console with a non-exclusive title is around 500k units and the most common value is around 200k, why take the risk? why spend their limited resources on a bet, when they can better use them in something that will generate them more profit like DLC for the other consoles, or even advertisement?

If all the publishers were SURE that their games will sell around 300k on the console they will be willing to port and pick up even some small profits, but with the small install base and the lack of support they get from the console owners, is a risky bussiness and they will avoid if they can.

1 mil is alot of money for a game that wouldnt make its return on investment for that system