Aside from not appealing at all to my sense of esthetics, I have no qualms about this because it does address a problem that a lot of people have complained about in a way that I could get the idea within a couple of minutes of reading the proposal. That said, a keyword might have been nicer.
Language designers seem to like to bang the drum about the ethos of "Orthogonal Features". I know Go's have, in presentations. But that seems to be cast off when the going gets tough. See also "Contracts" in Go generics, which is mostly the same thing as the existing Interfaces feature, but working around the fact that interfaces didn't have a good story for symbolic operators. Orthogonal? Smorthogonal!