I think it is more of a "nice to have" feature...you would certainly still want a cable for fast charging and data-transfer (although watch apple try and do away with wires).
If you had a wireless charging pad on your desk and on your nightstand, you might never need to plug in and use a cable because your phone would have plenty of charge. Don't know how much range, but I think I could install a wireless charger under my desk that would charge my phone in my pocket (my leg basically touches the bottom of the desk).
Also, they can have a strong enough magnetic pull to act as a mount. I've seen people use something like this:
In a car mount format. You just slap the phone onto the charging plate and the magnets hold it in place while you are driving.