Regarding the limited frontend capabilities, I had a similar opinion at one point, but with Shiny's HTML templating (https://shiny.rstudio.com/articles/templates.html) functionality one can circumvent the limited HTML that Shiny has out of the box. Besides that, there is also the possibility to communicate with R using JavaScript (https://shiny.rstudio.com/articles/communicating-with-js.htm...). These two functionalities combined allow for a frontend that is much more flexible, when compared to traditional Shiny applications. Of course, there might definitely be better solutions out there that fit your use case and Shiny's real use is primarily in sharing data analysis.