They have announced their own Samsung mesh Wi-Fi product, Samsung connect Home, which is due out later this year and is supposed to have a built-in SmartThings option.
Obviously that doesn’t help any current customers, but it shows some awareness of the issue.
If you have a V2 hub, it is supposed to be possible to Force a change in the zigbee channel but only by doing a complete factory reset. And you can’t specify what channel you want to switch to, you might even get the same one again. You just have to keep doing it until you get something that will work for you.
If you already have an existing set up, that would be a huge amount of work, but if you have mesh WiFi and you buy a new SmartThings hub, you could spend the time upfront to make sure you’re on a good zigbee channel.
Not a lot of help, I know, but at least it is an option.