Grid Cell Renderer - how is it going?

i dig my way through the customisation of Grid-cells. I successfully managed to attach a HtmlRenderer to a column and make it plug an FontAwsome.ICON in front of the cell-text. Looks fantastic !
However, what i miss is this: is it possible to modify the rendering of a single columns based on other fields of the row?
The renderer can see only the value of it’s own cell, but has no chance to lookup anything else from the datamodel.
If the interface would provide a reference to the current row, then all the other columns could be queried as needed.

Is that an oversight of the API-designer ? or is there a technical reason ?

… and when i look and think about it: the Renderer-implementation runs in the server !!!
Does that mean, whenever a column has a customized renderer attached to it, all cell-values travel to the
server - and back - to become visible ?
Let’s say we have a real-world grid with 15 columns (each with a renderer) and on one of these fancy modern large displays we can see 40 rows - and someone presses ‘sort’ - will that result in 600 roundtrips ?