Delta Airline Fare changes

When a consumer checks for an airfare they are always warned, "prices may be

higher" however, consumers are never warned prices may be less and if you

book now, you will not get an adjustment. Today I learned my flight to

Spain in Sept has gone from $785 RT to $706. I have two tickets so the two

tickets are $158 less. I called Delta airline and they said the fare would

have to go down $200 to make the change worthwhile because the penalty is

$200 per ticket to reticket at the lower amount. If the fare dropped $220

per ticket I'd only reap the benefit of $20 with a change fee. Something

seems seriously wrong. The plane is currently less than 20% full. What

incentive is there for consumers to purchase a ticket 6 months in advance

if rates are likely to come down. I mentioned that at booking there website

says there is a rate guarantee. I was told that doesn't apply to this type

situation. I don't expect airlines to alert ticket holders that a fare

has come down, however, I do think an airline should adjust fares for

consumers who find out that a fare is currently less. Other then

broadcasting on to the internet that consumers should think twice about

ticketing early, what recourse do I have?

Thank you.