Properly tensioned and laced Sapim Strong spokes are only 13-14ga butted spokes but can hold a surprising amount of power. Ebikes use them a lot on their small-mid sized motor builds for their great balance of weight and strength and modest price. I bet for most chinagirl builds they would hold up for ages.
I think the 12ga size is popular because a lot of people are running generic cheap no-name spokes which are weaker than name brand spokes so you have to go thicker to make up for it. Your typical $20 ebay 14ga spoke or the stock walmart wheel spokes are nowhere near as strong as a name brand spoke. Just like the chinese hardware isn't as good as the same sized bolts from Ace or Lowes - they use cheap materials, poorly die cut threads instead of properly rolled, and are often cheap plated steel instead of stainless that will fatigue and crack.
10ga should be limited to very powerful builds like KTM clones and big 4strokes that are using moped or motorcycle hoops to properly tension them and are silly to use on a bicycle wheel...a big 10ga spoke won't help your wheel if your rim can't handle the tension required for them or if the thin bicycle hub flange becomes the weak point.
