[grasshopper2218]

I don't think it saves as much time as it's often touted to. I've found the OP's point that you spend double the time to make the write once promise true more of a factor. I believe that what everyone is seeing currently is very small deposits of code being used in new apps. Wait until those apps become 3,4,5 years old and the strain of feature creep will start to show just like it always does in software.

I think the main advantage is the flexibility of it. Just like you said that you "love building the UI with React", then go for it. Personally I love Xcode and Android Studio. The ability to run the app right out of the box, and the performance measuring tools, especially when it comes to threading, are unmatched to what is offered in Chrome. Whatever suits a developer's passion and skill, to enable them to build with a CHOICE of languages and tools, that's the main benefit of React Native. It also introduces a bunch of web developers into Kotlin and Swift, and they might get a taste of it being not as intimidating as they think it is.