Contact me with questions about data science, start ups, or R - if you have a data backed start up, R + Shiny is the way to go.
Personally if I wanted to use R I could just interface with it from another language (Python, .Net, Java etc.) I haven't played enough with R recently to make an informed opinion on the current quality of its network libs and framework stack however it seems like an interesting gamble (that's paying off for you all?) given where the focus of the R community has been (statistical programming rather than general use) and statements on the front page of "No web development skills are required."
We could interface R with another language if we needed to... but we're a data-science company, and unlike many other co's or startups out there, we hire data-scientists who write features and applications directly. R makes this possible.
We have an Android App as part of our services - we use RServe as the API interface so we can call R functions from the App.
To your other point - web development skills are most definitely required, as are good engineering practices, and a stable stack. Shiny is just like any other framework; it takes a range of skills to create an application people want to use and pay for.