There are two occasions you might encounter a need to be on that side of the lathe. If you ever have someone in your shop that you are teaching, and they are left-hand dominant, being able to turn from that side of the lathe makes bowl turning easier. I teach, and while most left-hand dominant people have learned how to do most things with both hands, I have had two people who simply could not use the bowl gouge safely on the side of the lathe that right-hand dominant turners do. They were grateful I could still teach them, as was I.
The second time might be if you were turning a bowl that had very steep sides, with the rim turned inward. Think Calabash style, but very exaggerated inward turned rim. Being able to stand on the opposite side of the lathe to get that interior rim turned is the best way to do it, unless you have a sliding headstock, or very short bed.