Based on discussions earlier, here's what I think has happened.
EA has, for a little while now, been in the process of cementing their next gen plans. And I don't mean a vague list of titles, but how to best manage their finances, which titles and franchises to focus on, and what technology will be used by their studios.
Early on, and I mean really early on, they probably intended to bank on the Wii U. It would make no sense not to. Priority was probably on Sony and/or Microsoft, but Nintendo was always part of the equation. However, a change in circumstances has lead them to put their money on Microsoft and Sony's horses instead.
Firstly, EA is focusing more on established AAA titles, and new AAA franchise. Far less so on the middle games. This is your Mass Effect, Dragon Age, Battlefield, Madden, Fifa, and so on. These are big budget title with blockbuster production values, intending to push cutting edge technology to high levels. The alternative to these games is their F2P offerings, like Command & Conquer.
Secondly, EA is pushing Frostbite 2.0 internally. It is to be their engine for their games, especially for their AAA titles. Frostbite 2.0 is a CPU heavy game, that is far better suited to powerful CPU computing than low-middle tier. Whether or not it can run on the Wii U is irrelevant. If rumours are correct, the Wii U's specifications, especially in the CPU department, may have fallen short of EA's expectations. Especially for their expectations of what Frostbite 2.0 will require, based on internal advice from technicians. Given the focus for next generation from EA will be on AAA Frostbite 2.0 titles, this suddenly puts the Wii U in a difficult position.
Thirdly, conservationism in direction. EA is doing the above, with their focus on the traditional Microsoft/Sony market. They're so wary about expanding, acquiring new IPs, and risking investment in non-target platforms that they, for example, didn't even bother to bank on anything from THQ's fire sale. Once upon time this would be very different. Today, not so much. Whether or not you agree with their focus or whether or not it will actually work is irrelevant. The point is they have a focus, and the Wii U could very well not be part of that picture.
As a cherry on top, they probably had difficulty working with Nintendo in regards to what to expect from the Wii U. You're not going to get conference level "unprecedented partnership" bullshit unless it's actually intended. This all happened almost a year and a half before the Wii U launched. I suspect Nintendo was still finalising details of their system, especially in regards to online hardware, and at the time EA expected A) more flexibility in the online service, perhaps with Origin, and B) a stronger system.
Had the Wii U steered much closer to Durango and Orbis we might be seeing different behaviour. However, as it is, the huge hardware gap simply favours EA's next generation plans far more than what the Wii U offers on its own. They may simply believe the technology struggles of having their blockbuster AAA games pushing Frostbite 2.0 down to the Wii U enters a realm of marketing and production that is not on par with other platforms, as in it becomes very similar to the 360/PS3->Wii situation. Again, not really a case of "can this work?", but "does this meet our goals?".
And at this point in time, the Wii U does not look to be part of their next generation forecast. EA has picked their horses and bet on them.
