I chose to allow and relay dust, I do accept it would create huge traffic and volume and possibly open up to satoshi attack but I have a good reason, Bitcoin will become $1m+ per coin making a satoshi worth trading! Dust now is a pint of beer in the future!
If it ever becomes a pint of beer you can change your node settings to allow dust. By allowing worthless spam, you are actually decreasing the likely-hood that Bitcoin will be successful long term by increasing the cost to run a node and thereby reducing network security. There is literally no reason to accept dust.
Like DeathAndTaxes said, would you spend $0.49 cents to mail a penny? More accurately, would you spend $0.49 to mail a penny to a PO box that someone else has to pay a monthly fee for to keep just to hold your worthless penny for eternity on the hope that it might someday be worth
at best $0.49?