For the buyer yea, it's stupid, if the seller wants at least $20 then they should start the bidding at $20 not 99 cents, right?
But for sellers I think I has a place, if I understand it correctly...
Say you have a widget you want to sell.
You do not really know what it is worth but you want no less than $20 for it.
You can list it with a 99 cent starting bid but do not have to sell it if you do not get bids of at least $20.
Now I believe you do not have to pay ebay listing fees if your reserve is not met and you get to list it again for free.
It lets you as a seller see if the item is really worth what you think it is and not be forced to sell something at a loss.