er collets are standard tooling now due to the cnc revolution in even small shops.They grip much harder, especially useful when using dovetail cutters etc, As for height issue when you have something big on the table or a dividing head those few inches r8 collets can save make it a yes or no job.Riser blocks are good but hard to find and sought after.
Also in using a collet chuck albiet clarkson or er, when doing tool changes your not undoing the drawbar which is much slower