Yes, I wonder why this is not (yet) possible. It would be so helpful to have 'Filter by' activated! (Especially seen that most of the default views are sorted by Name which is useful if you have a couple of entries (micro enterprises) but which is of no use at all if you have tens of thousands of records (you start pagination as all the thousands of accounts that begin with 'A' show up first...). 'Filter by' comes into play... (I know there is the 'search this view' field but in some cases you want to filter not search). If we add the description field to the list we even cannot sort it (nor 'Filter by'). Both would be of added value.