Well, the main advantage of WireGuard then seems to be it doesn't give you any options, so you're less likely to mess it up. Of course there is only one (two?) implementation(s) of it, so "interoperability" as such is not really a thing.

IPsec can be/is complicated because we learnt as we went with it, but given the correct settings, it can be/is secure.

So just like with SSL/TLS, it may be necessary to 'simply' introduce new RFCs to deprecate the Bad Way(s) of configuring it. Doing a quick search, there's a BCP RFC:

* https://tools.ietf.org/html/rfc5406

(I haven't really used either, so am just spit-balling here.)