A requirement for the proper operation of the grid edit functionality is to rebind the control when a row is switched in edit mode. Here is some basic information which explains the necessity for automatic rebind on edit.
Why does it need to do a postback just to set the row into edit mode?
Currently you can set grid row in edit mode using postback or callback (if the grid is in AJAX mode). We consider this approach suitable and safe because the grid now fetches the latest information from its data-source (making trip to the server).
Why does it require re-binding?
Getting the latest data from the grid source ensures the consistency of the displayed information. That is the reason why Telerik RadGrid performs automatic rebind when the user switches the grid item in edit mode.
Creating edit form and populating its fields with data on the client is not secure as at the same time other users may change the database content. This will result in data inconsistency.
Moreover, the entire process of client edit form generation and its subsequent submit on the server (to reflect the changes) will tremendously slow down the control's performance. That is why our developers have not included this feature in the current grid implementation.