Since the OP is referencing ventilated seats, "recent" is relative.
There's a couple of components.
1) Simplification. Previously the options were all customizable. When I built mine, I had the ability to select any color interior to match with any color headliner. Interior trim alone had half a dozen options, now there's 3 and it's dictated to match. There were also much more hardware options - speakers, roof, rear facing seats, subzero package, suspension were all different built/hardware configurations. That has an effect on sourcing, time spend building, inventory storage, etc. Now, there's significantly less configurations. Premium upgrade, sunroof, and rear facing seats is it and RFS should be on it's way out soon.
2) Scale. It's hard to scale without simplification. Once simplified, they were able to increase production speed. Overall adoption helped here as well as did the learning curve.
3) This may be unpopular, but it's only a perception of cheaper. Tesla had price increases along the way, as well as bundling of packages, before offering a price reduction. It isn't neccesarily any cheaper at the end of the day.
As an example, I just built a 75D as close to mine as possible. The significant differences between the new build and my original are - I don't have power liftgate. But this new build doesn't have the subzero package - heated rear seats, wipers, mirrors; or the alcantra headliner. The overall price of the new build is $800 more than what I paid. Meanwhile, I also had full customization and control of the combination I wanted.
