Using my Eye-Fi to send images from my camera to Photosmith on my iPad has been a huge productivity booster for my entire workflow. I do all of my rating & reviewing in the field either during or immediately after a shoot, and when I'm working with a model, she has the ability to tag her most and least liked images as well. When I get home I import the RAW's into Lightroom as usual then do a metadata-only sync from Photosmith on my iPad to the RAW originals that I just imported into Lightroom, and I immediately start editing.
Although I have no plans to replace my 5D3 anytime soon, there's absolutely no question that integrated WiFi will be a requirement for my next dSLR body. It's an invaluable tool.
I agree with Juga's comments earlier, if integrated WiFi simply causes you to think about social sharing options then you're not seeing the bigger picture.
Guess it depends on which larger picture your talking about. I shoot pretty much entirely in raw and post process everything. I don't own a tablet and even if I did I'd still most likely not want to try to process images on it, so before anything gets uploaded or shared anywhere I'll be putting it on the PC at home first and running it through photoshop. As a result the only thing Wifi would really do for me is make it so I wouldn't have to plug the little usb cable into the side of the camera to transfer the images to the PC. Not exactly a feature worth dropping much money on, at least not for my workflow.
Obviously your mileage varies, and that's ok. But the feature itself doesn't benefit everyone in the same way.