When BTC is trading at over $1000 all of that "dust" is going to be worth alot. If I can only use BTC to transfer large amounts of cash I would be using it much less than I am now.
When BTC is trading at over $1000, they'll change the rules regarding dust transactions so that it's value is sub-cent again.
Logic.
How are they going to adjust the dust amount on the fly when BTC are trading at $650 USD on week and $200 USD the next week? Maybe letting miners decide what to include in the block chain instead of hard coding it into the software perhaps? I thought the whole point of this system was to let the market determine what works and to avoid using some human decree as the law of the land.
It will get changed with new versions of software and the devs will average the recent fx rate to determine the dust value.
It is utterly irrelevant that the dust value might be equivalent to 0.65c one week and 0.2c the next. If Bitcoin is a world-beating currency then dicking around with sub-cent transactions is like mostly using your Ferrari to go down your driveway to collect your mail.