The motive for doing this is that I want to open other ports so that I can evade firewalls which block VPN connections. Instead of redirecting eg. port 53 or 123, I could simply set up a destination NAT rule (my router allows 'easy' port forwarding or you can set it up manually with a destination NAT rule. using the DNAT method gives you more flexibility like specifying IP addresses) which doesn't specify a source port, effectively redirecting all traffic going to my router on every port to the WireGuard server.
The benefit is that I have the best chance of being able to connect to my VPN server (I won't be talking about DPI or TCP/UDP converters since that's another topic)
My understanding is that the security relies on the daemon that is running (or will be running). So I'm fine in this regard since its all being redirected to WireGuard. But I've never seen this recommended at all. I've been doing it for a while and I do get a lot of connections from random IP addresses. I'm not sure if that could allow attackers to DOS my home network more easily, cause they have more ports to send data through at the same time.