In the past the admin section of a web application tended to be built solely for functionality, with not much, if any at all, consideration for the design side. Thankfully things are changing. Functionality and design, especially over the last couple of years, have been merging. And with the huge rise in popularity of the Bootstrap framework, creating a beautiful and functional admin panel has never been easier to create.
Why would you choose to use Bootstrap at all? Well, with Bootstrap, you know exactly what you are getting. It is a relatively easy to customize mobile-first framework that includes ready made design patterns and comes packaged with a huge library of components and widgets. And perhaps more importantly, your Bootstrap build will be consistent on all screen resolutions and platforms. So it does make sense to build the dashboard or the admin panel of your web application with something that you know works well.