If there is no payment function, what meaning does it have in addition to speculation?
When people say that Bitcoin can't be used as a payment method they usually talk about slow transactions and high fees. It doesn't mean that it realy can't be used as a payment method (just take a look at all those crypto cards and services like bitpay etc.), for now it is just less convinient then credit cards.
Why is the use of blockchain technology all talked about is not focused on the application of virtual currency in retail payment?
There is a pretty big amount of coins with instant transactions and almost zero fees but the whole community is keeping a close eye on bitcoin that implementing changes very slow. It doesn't mean that no one is focused on it. You just have to be patient because it is risky to change BTC related stuff.