We have discussed your suggestion and the scenario with the too small last column. It seems that you have set fixed Width for the GridView and the rest of the columns, so the last column will be shown with a minimum Width.
I have checked the behaviour with the MS DataGrid and actually it is the same. We have done our rendering mechanisms to be synchronous with the DataGrid and currently we do not have plans to change that behaviour.
You can set a larger Width for the GridView or leave it with Auto Width so that the last column can take all the space it needs.
All the best,
the Telerik team