I don't think it's unimportant. I think clarity and disambiguation in communication are more important than strict adherence to a convention, and as far as I can tell °K was folded into K because the temperature interval °K is identical to the thermodynamic temperature K and the CGPM picked K because it more correctly conforms to the SI convention of single-letter unit designations. I get why they combined them, but considering that °K is (or was) exactly equal to K I prefer to use it to typographically distinguish it from other k-types in my writing, especially if I'm writing equations by hand. I've been reading up on the CGPM proceedings around defining the K and I think there are good pedagogical reasons not to use °K when introducing the concept of thermodynamic temperature to students because it isn't a degree on a scale like Celsius, it's a plain old base unit just like any other. It may be that I'm just old enough to have been indoctrinated into the °K school of thought and now it's ingrained but in any case the visual distinction helps me and, since it is identical to K I don't think it introduces any new confusion. I probably wouldn't use it if I were teaching physics in high school but for my own use? °K all day.