LightSwitch has HTML Client option as well as Silverlight.
It has a sweet spot for usage for things like putting a quick GUI over data and allowing you to customize portions by coding around events.
Let's say I write a new website for my companies clients, and the enrollment and features of each client are driven by a database. I can code a backoffice application for boarding and maintaining those customers, or I can quickly stand up a GUI in a tool like Lightswitch or Wavemaker, and spend the saved time making the client experience better, rather than investing it in boilerplate maintenance code.
Is it for everything no. But neither is XAML, HTML, DirectX, MVC, etc. Choose the right tool for the right job. Currently for some data driven LOB applications LightSwitch is one of many tools that can be effective.