Until recently, it was possible to add money directly to my USD balance by placing a limit buy order on the Lindex at a price that was unlikely to fill and then canceling it. When the order was placed, my payment method would be charged, and when it was cancelled, the money would be added to my USD balance. Recently, LL changed this so that the money is now refunded to my payment method.
It is important to me to maintain a significant USD balance because it is a bulletproof way to make sure that I don't lose my account for nonpayment should RL circumstances not allow me to logon for an extended period. I doubt that I am the only person with this need, though I doubt it is common.
Now, the only way to add money to one's USD account is to buy Linden dollars using one's payment method and then sell them. Both steps require payment of fees. It really isn't reasonable to require payment of two fees just to deposit money to one's balance.
Please provide some way to add money directly to the USD account, like a choice on some appropriate page to "Add to USD balance from payment method."