One of the very big hopes for Bitcoin was the notion of enabling 'micropayments'. Today, one can't practically pay 50 cents with Visa because there is a 30 cent swipe fee and a percent fee on top.
However, now with the stalwarts of 1MB blocksize limits, it looks like we are going to have to start setting our miners fees to (remarkably enough): 30 cents.
Does this spell an end to micropayments?
Only time will tell.
I believe micro-payments are what will really push Bitcoin/bitcoin to mass adoption one day.
Any amount, around the world, any time, without trusted parties. That is special.
But as I have said, only time will tell.
Machine-to-machine payments are hugely important concept. This will be totally suppressed if we get stuck with the same high transaction fees that Visa has. Side chains tend to be unreliable and proprietary letting a 'middle man' tax traffic on that medium. I think we should be careful to preserve the notion of micropayments and let blocksize go to 20MB to avoid log jams and corresponding high miner fees.