I hope people requesting this feature know that it is a CPU intensive process to go over all the items in the dataProvider to find out maximum width required for all the columns. If the number of visible columns is more it would take even more time to compute the values and layout the columns.
If a labelFunction is being used at DG or DGColumn level and custom styles have been used on a column for fontSize for example, it complicates the computation even more.
When the data is being paged from a server it is not possible to compute the smart width at all without requesting all the data from the server, which is never desirable.
Keeping these things in mind I feel it makes sense to have a flag on individaul DGcolumn (apart from one on the DG itself) to control the computation of smart width. If the flag is true width is computed and false would use the normal way of determining the column width.