As much as I dislike SD's (and other's) abuse of the blockchain, this is a bad idea. First, any idea that is admitted to be "temporary" should be suspected of being a bad idea. Second, IMHO, it is philosophically wrong -- at best a band-aid for a bigger problem that needs a different solution. Third, it's debatable whether or not this change will alter the behavior of those (ab)using the blockchain.
All good points. Another reason this should not be permanent, at least without some more thought, is that over the long term, while these "lost" dust amounts are insubstantial, there could ultimately be substantial (and unnecessary) permanent loss of BTC. There should, perhaps, be some way of recombining these lost amounts into something useful (without costing more than they're worth).