I don't think that micro txs are the real issue (the pricing of tx's using tx size and coin age stops spamming without fees) but instead the handling of a large # of txs and in some ways we can thank SD for giving the system a bit of stress as it is now obvious that further development (much of which is already underway) is needed in order for the system to scale up (which will be necessary if it is to ever compete with the likes of a payment processors such as the current credit card ones).