The consensus is that rabbits chew wires because they look like roots. They will snip them in half to get them out the way as if they were burrowing. But this doesn't explain why they like just chewing on wires that are not in their way. The Internet tells me rabbits might be able to hear the frequency of the electricity pulsing through the cables and this annoys them but I couldn't find any other articles backing this up.

Nybble definitely only chews cables that are in his way as I discovered yesterday when he tried to get past my computer which had my Sony camera USB cable sticking out. I fortunately still have a sony USB cable, but minus two plugs (which I didn't use anyway).

Pixel however loves to chew. He has brought the internet down in the flat and eaten the phone cable twice. Steven's laptop cable was totally destroyed costing in £60 for a replacement. His new cable has bite marks in it and Marks cable has bite marks covered in duck tape. This is what happened when we gave him a cat 5 to play with:

Pixel is so sneaky about it too - he will slowly idle up to the cable looking all cute and innocent. And then ATTACK! I am surprised he is not dead yet from electrocution.