Some saws come with a plug with too hot of a heat range. Just because it comes from the store like that doesn't mean thats optimum.
Even if manufacturers can make better parts, its cheaper just to buy parts from some other distributer (Champion, NGK, Autolite) than make the plug themselves. Do you honestly believe that a saw manufacturer is going to pay for the tooling to make their own spark plugs when they can easily just add 1mm to the bore of their saw and call it a day? It doesn't matter how many saws they make. Its always cheaper to outsource a generic part than come up with the tooling to make your own.
It's very common that manufacterers develop a particular component together with an independant subcontractor, and take exclusivity rights for it. if Stihl for ex. were to be seeing advantages in a particular plug design for their saws, it would be relatively easy for them to find a plug maker and agree upon exclusivity, provided that they share development cost or commit to certain sales numbers, and if the design can be protected by a patent.
A lot of people have the "you can't make it better" attitude. A lot of saws have less than optimum porting. Why is that? Ported saws cut faster than a stock saw. Why didn't the factory make the ports the same as in a ported saw? If one manufacturer was really trying to get an edge over another, don't you think they would open up their ports a little? I'll give you a hint. It doesn't have to do with emissions. Saws made before the EPA cracked down can be ported too.
Most people don't care. I'm probably just :deadhorse:. sorry.
don't get defensive. It's OK to think outside the box sometimes, but I agree with Philbert, that if the plug design you promoted is so much better and simple to do, why do plug makers not make them standard like that ? I suspect that your design has indeed some negative effects to it, that make them less universal in use or create some minor risk.
If a modification is proposed like you did, it's quite normal that people start debating it and ask questions. We try to understand.
Same thing for the porting issue. You don't generally produce saws for a niche racing market, but for the entire pro/consumer market. That, along with some emission laws, do force saw makers to sign for a lot of compromises, and results in a product that adresses the needs of the majority of the market.
Folks on this forum has outlined enough what modding can do to a saw, but saw makers think different for obvious reasons.