I'm with Radeng on this. The rules are there for a reason.
In addition to all those antennas, there is also the simple fact that all electronic devices have a series of characteristic frequencies, based on the various electronic switching frequencies inside them. As the world relies on relatively few chipset manufacturers, the chances are that the emissions from one device will match the susceptibility characteristics of another. Not to mention various noisey motors etc. The emitted signals are incredibly low power, and techniques such as shielding, filtering and segregation are used to minimise the risk. Ultimately though, as aircraft equipment is very sensitive and there are so many routes for the interference to inject itself, the risk is there, and in practice is unmeasurable.
As far as I am aware, no-one who has any knowledge of the subject has ever said that the aircraft will roll over and dive into the sea because of interference. What it can do is cause glitches, mis-leading information etc. that can cause the pilots distraction. Therefore during the high workload phases of flight it has been chosen to minimise the risk by removing the potential source of interference. This seems reasonable to me.
As for the rules, they are the rules. I carry a laptop with me. It is designed, and regularly tested, so that it does not produce interfering emissions when operating (well as long as the wireless connection is switched off). I know for a fact that this item will not interfere with the aircraft at any time, but when on a commercial flight I switch it off during take off and landing, as I am instructed to do. It is the rule, and I do not expect an exception. Unless you are an expert in EMC, and an expert in that aircraft's systems and susceptibility levels, then you cannot say anything with any certainty, so shut off and put up with it.
There, it's good to get that off my chest.
Well said sir, the funny thing is I have never seen a pilot abide by these rules!