Q1. I don't live in Europe. Wire transfers from my US bank can only be sent domestically, cost me $20, and require me to fill out a form and then stay up until 2AM so that a person can call me on the phone during business hours in the US and I can confirm that I did in fact fill out that form. Wire transfers from my Japanese bank are more reasonable but cost 10000x as much money to send and (under ideal conditions - during business hours long before closing on a weekday) take longer to settle than modern cryptocurrencies.
Q2. Why should Apple stock exist when we already have dollars? Why should Brazilian Real exist when we already have dollars? I wouldn't trade USD for BTC for EUR. I would probably trade USD for EUR directly. As a consumer, the best place I can do this is FTX, a cryptocurrency derivatives exchange, because they provide end-users with the extremely competitive forex rates of a Hong Kong bank's OTC desk. The second-best place is probably IBKR which provides extremely competitive rates because it's literally a forex broker but takes days to wire money in and out. The third-best place is probably Shinsei Bank, which is one of the two most popular banks for foreigners in Japan and provides suspiciously good forex rates compared to all other consumer banks in the world.
Q3. "Smart contracts" are not really a replacement for the legal system. They are, at least for now, mostly a way to build non-custodial versions of traditional financial products. Again, this is sort of like saying "Why do we have oil futures and SPY puts when you can just buy oil or sell SPY?"
Re: Conclusions: Ok, but did you try to use the internet to let your US customers pay you dollars which you would then give to your US creators who create pornography for your customers? How many providers accepted this proposal? What fees do they charge?