You specifically said you can't use your phone while charging. I specifically said that you CAN use your phone while charging.
My solution divides the number of times you typically use the USB port by let's say two hundred. Do you suppose that affects the amount of wear on the USB port?
You want me to "admit" that buying a charger costs money (which is obvious, and I already said the charger costs less than $10) and yet you don't specifically admit that you have zero experience with my solution. You mention a problem you had that I never encountered with the four Nokia tablets I've used external chargers extensively with.
Using an external charger is better than not EVEN IF THERE WAS NO USB PORT PROBLEM. When I started doing this with my N800 the USB problem didn't exist. I am using a similar solution with a non-Nokia phone as well. (A Palm Centro.)