I think most everybody appreciates changeable backstraps and grips. Less common on a poly frame due to the simple, thin, lightweight design. A thin factory poly grip with the option to screw on a bigger grip like a Hogue is cool.
I'm not sure how a striker-fired decocker would work since you'd have to rack the slide to re-cock it, thus ejecting a round. Unless you innovate
How about a changeable front strap since people have different finger sizes and groove preferences? I prefer the thumb button mag release. Sights depend on the application, but removeable front and rear are a huge plus for me. You're surely not off-base, as long as your trigger is quality it will find a place.