I had one of those bobbin winders, recently gave it to my sister-in-law. I have Babylock machines and the bobbin winder didn't wind the bobbins full enough it seemed.
And, two of my machines have separate bobbin winding spools and I can wind a bobbin while I am sewing or embroidering.....if you don't need the color of thread you are sewing with to do so! LOL
The bobbin winders are popular, many love them.