I was reading about Nikola Tesla today (via the Oatmeal) and read about the Wardenclyffe Tower which (among other things) was intended to transmit electricity wirelessly. Forgive the naivety of the question, but if technology that could transmit electrical current wirelessly was invented over 100 years ago, why don't we use wireless electricity in our day to day lives today? In other words, why do we have to physically plug in our electrical devices (phones/computer, etc) if there exist such a thing as wireless electricity? If its an issue of efficiency/cost then I would imagine that some rich people still wouldn't mind paying extra, in light of the waste, for the added convenience.
Please explain in layman's terms (though a simple answer would suffice).