It is not here to replace anything but to help fast track transactions and make it cheaper.
The purpose of bitcoin to be a microtransaction payment.
Not sure if you're trolling or you simply don't know anything about bitcoins at all. You have to pay more transaction fees to have your transaction prioritized. Do you really expect someone who paid less fees to have a faster transaction? Bitcoin can be determined as a lot of things, just like everything else. It can be determined as a currency, as a commodity, or anything you like, there's no limit as long as you can imagine it.
Bitcoin is definitely not for microtransactions. As a matter of fact, it's one of bitcoin's problems. It can never be used for microtransactions since the fee is already high. The fee is more than one dollar now, so doing microtransactions would be unwise. On the other hand, transacting millions of dollars through bitcoins can have this amount of fee as well. More than one dollar is enough for your transaction to go in smoothly.