I agree the map is the ultimate tool. However, I do think that being able to quickly view a single geometry from within the grid makes a lot of sense - and for users who want to easily visualise a single geometry, will be a great deal more convenient than the map.
Note that I'm not talking about anything complex here - just a convenience panel that renders the geometry, and maybe has zoom and scrolling. The viewing tab would be where the real magic happens - handling the map overlay and the ability to display many geometries at once.
As a user, I would agree with Dave here. A good example is a table that holds the polygons of each county in the U.S. or each country in Europe. It would be very helpful to view each individually as well as collectively if I were to select all in a query.
