It’s all about money and production time. Also, “roasted neck” is a buzzword for marketing purposes. Torrefied wood is the goal. Roasting the wood is a process of baking it in an oven under pressure at a certain temp for a certain amount of time. This forces the wood to become “torrefied”, by baking out all the moisture. This is not the same process as kiln or air drying the wood. All wood in all guitars becomes torrefied over time which is why vintage guitars are much more stable to humidity change than new guitars. Forcing the wood to become torrefied vs allowing it to occur naturally is now a marketing thing which has led to you wondering about “roasted necks”. Honestly, with a modern fender neck, if the maple is cut correctly so that the end grain is flat sawn, then wood stability is not generally an issue making the “roasted neck” just a marketing ploy. I can make a non roasted neck look exactly like a roasted neck with a stain wash on the wood before finishing. Torrefication is a technique used by cabinet and door makers for centuries. When building a big double wide door it’s extremely important that the wood doesn’t change with humidity so that it will continue to open and close with no issues as the seasons change. Also, if they did this on all their guitars how would they be able to charge more for it? .....or create another new set of seeming endless new models to add to the already insane number of variations currently available?