I think you're looking at it from the wrong direction. Sure, it would cost money and change things taking a double stack design and reworking the PISTOL, so why bother. IF you have to rework something, simply create a single stack magazine that fits inside the double stack magazine body (shell).
So what if you don't get 10 rnds of 9mm in a single stack that fits flush with the frame? You can have 9...
But, again, why bother?? there are a LOT of fine single stack magazine pistols still on the market, even in 9mm...
The people to blame here are not the gun makers, but the LAW MAKERS, and the people who elected them. Its not so much a matter of the gun makers "not caring" but more a matter of simple economics, and cost/benefit analysis.
Consider, for a moment, the cost to the makers to make special versions of their products to comply with the restrictive laws in SOME states.
IF the cost of making/modifying their products just to comply with the BS crap put into law in certain states exceeds or even approaches the potential profit from sales in those states, they aren't going to do it.
And when certain states come up with extreme requirements (such as microstamping) the cost of converting production to comply grossly exceeds the money they would make in sales, and refusing to do business in those states actually saves the company money.
Yes, it sucks that you can't get the pistol you want with the features you want, ONLY BECAUSE of where you live, but the people to get mad at are the ones in your state that caused that to happen.
Instead of whining about "the gun makers don't care" why not spend that energy getting those people out of office and those laws repealed??