The problem is not the transaction volume, it is that the transactions which SatoshiDICE generates cannot be "pruned", and that the 1-satoshi outputs are economically impractical to ever spend.
I wonder if there would be any interest in a service that spends your satoshidice dust for you. The user uploads their (empty except for unspendable dust) wallet to the service, and the service spends the dust for free by combining it with old/large inputs.
It would have to be something satoshidice players did for the good of the blockchain, because the dust they sent wouldn't be worth enough for the service to pay them for, but it would be good to be able to prune the thousands of single-satoshi outputs that are out there.