They can be a way of avoiding a judgment creditor getting their hands on your money, and yet allow you to make purchases online, make payments online, etc., but yes, they are expensive.
There are other ways to work around this situation. If you want to buy something online, you can get a gift card for something like Amazon or Wal-Mart, (and many other stores) and then use them to make a purchase online. They have no fees involved, and do not expire.
Other things can be purchased through the mail using money orders. Or payments can be made through the mail using money orders.
And of course, you can try to buy everything possible locally and make as many of your utility and other payments locally as well using cash.