A good electric kettle will heat the water quicker and more efficiently than a microwave.

My microwave is 900w, which is at the upper end for a domestic one. My kettle is 3,100w, so you can see why it would be quicker. It's also more efficient. It creates the heat directly and dumps it straight into the water, without having to convert it into radiation first. The kettle walls are insulated so it remains cool to the touch - that's for safety and also ensures all the heat goes where it is needed. It's also more convenient to use because it's form factor is a jug. It's cordless. It detects when the water is boiling and switches itself off - something we take for granted in the UK, but when I was in the US it was rare.

Electric kettles are wonderful. And relatively cheap. It's definitely worth having one in addition to a microwave.