The Swedish/Finnish keyboard also has a § key next to 1. I find the character rare overall: I see it found it only in law text, bylaws and contracts -- that I have never got to write.
On PC/Linux, Shift-§ is ½, and the Alt Gr legends are ¶ ¾, where ¶ is the paragraph sign which I also never use, but sometimes see as end-of-line marker in text editors and word processors.
On Mac, Shift-§ is °, which under Linux is on Alt Gr-Shift-0.
I find it easier to type fractions with the Compose key than to remember which combo each one is on. To get ½, I often just type Compose 1 2.
Should I ever need §, it is available on Compose s o, Compose o s and Compose s '!'.
BTW. The olde Amiga which I once had learned to type on, had '~ on the key even in Swedish/Finnish layout.
On PC/Linux, you have to type Alt Gr + " and then Space to get ~, whereas on the Amiga Alt Gr + " gave you ] (compare US-ANSI).
So: no, I don't think the section sign needs to be more common.
The Compose key should be more common, with a "Compose" key in every keycap kit!