I wear gel shoe inserts because I am on my feet all the time. I work in retail and my feet really hurt by the end of day.
The gel inserts provide a cushion that makes it more comfortable to be on my feet for long periods of time.
The only disadvantage I have found to wearing shoe inserts is that you can only wear them with certain types of shoes.
In the summer when you want to wear sandals or shoes that don't have a closed heel, you can't wear your shoe inserts.