All of which...
...helpfully demonstrates my point for me. Your first citation has the direct quote: "...no direct correlation is being made between electronic interference from personal electronic devices and plane malfunctions". I strongly agree with "some experts" referred to in this one who say that "these anecdotes are not enough to draw conclusions".
Your second citation doesn't refer to personal electronic devices, but the installation of access point gear in planes which only vaguely correlated with some problems during "ground testing 'at elevated power levels'".
Your third citation, another direct quote: "despite all of the studies that have been done, there is really no hard scientific evidence that cell phones, or other devices, actually interfere with the navigation and communication equipment on aircraft" and it goes on to say that all the evidence is anecdotal.
I'll barely even dignify the fourth "citation" with a debunking. It's actually from August 1994, if you look here: http://newspapers.nl.sg/Digitised/Issue/straitstimes19940807.aspx and it is pure hearsay and anecdote fuelled by paranoia.
In my eyes, there is as much basis for not using wifi on planes as there is for these poor people thinking their collection of (possibly psychosomatic, or possibly physical and unrelated) symptoms are caused by radio waves: http://www.bbc.co.uk/news/world-us-canada-14887428
This leaves you with the argument: "well, it might cause a problem, and I'm not willing to take that chance". If that were a valid argument in its own right, none of us would be using wifi or mobile phones at all "just in case" they cause cancer (which, incidentally, also has no evidence whatsoever to support it). The evidence for electronic devices interfering with planes is so slim it's practically non-existent.