This is often a returning topic here on HN where most users probably work in startups and/or companies with consumer facing apps. Those would want every platform to have the look & feel of the platform you're running on. Although... Seems the new version of iOS Skype is WP8 styled and feels a bit alien on iOS while it's not unpleasant at all. So not sure if I agree always. Anyway; if you have apps for internal use or use with partners, it is actually often better for the apps to be 100% identical on all platforms as that will save tons of support calls. That's why a lot of companies just do iOS first, design it for that and will make the Android version exactly identical. To save time there, often HTML5/Cordova is used for that by internal departments / IT, but I know you can make MUCH nicer apps in the same / less time if you use Xamarin (Forms or Metaframe) (or maybe a solution like this) (although I cannot imagine IT would pick JS over .NET or Java, ever).

I think for many apps out the codebase is dominated by UI code, and the business logic part is small and relatively easy to write anyway. From personal experience, sure, I have some classes that abstract away server APIs and some classes for data models. But most time and sweat goes into getting the UI to look good and performant on different devices.

Say, for an app like Timely [1] which I'm a fan of, I would think the data models for timers and alarms are trivial, and the code for all the subtle animations is where all the meat is.

[1] https://play.google.com/store/apps/details?id=ch.bitspin.tim...

This is really the way to go. Customize the UI to the platform make the app as polished as possible, but don't give up cross-platform business logic/unified deployment.