Because of the cost involved in setting up a channel. It's still not suitable for paying for a coffee or restaurant for example... Unless the cafe/restaurant h

Because of the cost involved in setting up a channel. It's still not suitable for paying for a coffee or restaurant for example... Unless the cafe/restaurant happens to have an existing channel with an exchange that you yourself happen to also have a channel with; then you pay through that exchange... You can see how in this hypothetical word, it would be better to have fewer exchanges... More centralization.