Reason for declining: Cannot anticipate the desired widths in the ColumnGroups child Columns. For example: a Column Group has 3 child columns with fixed by the user widths, there is no way to anticipate the expected result widths when re-sizing the parent ColumnGroup.
It is possible to resize column, but if columns are grouped it is impossible to resize whole group. This feature will improve user experience of our tables with large numer of columns.