The Vietnam visa website seems inaccessible from Thailand for some reason. Using a VPN or a browser with a built in VPN (opera, brave) did the trick for me.
Note on the Vietnam visa application that where it says "given name" you have to put your first and middle names. There is no field for middle name. I neglected to do this, only putting my first name. This resulted in having to pay 130 USD online for a rush visa service at the airport in Siem Reap so that the visa would have my full name on it. I'm pretty sure the airport personnel get a kickback for facilitating it. Several other people there had to do the same due to issues with not filling out their visa application correctly.
On the plus side, I got concierge service upon arrival at Da Nang and got to skip the long immigration queue.
Of course you're right. A weak currency can have all sorts of different effects. I'm just suggesting that the statement "this is good news" is a little humorous. Note that a weak currency can have negative effects on everyday people as well, not just rich folks seeking to travel and buy giant Toblerones in airports.