could you make an (optional) expand all / callapse all buton in the header of jqgrid's containing subgrids? That feature seems to be convenient for some.
However, I also think that we might need a custom CSS for each cell and formatter shall not be used for it (because it clashes with some other stuff, like in my case).
So one vote more for a new feature, something like cssUrl : 'someUrl'
This is something it seems we'll need (even more complicated binded with more features), you can use gridComplete to change CSS of rows/cellscurrently after the grid is rendered.