FB currently supports VBScript, JavaScript, PowerShell and Python. I think many users of FB are less familiar with these, and more familiar with C# or other .NET languages, or Delphi.
LINQPad is a popular high quality tool that directly uses .NET to run C# source, and also VB and F# , pretty much as if it was interpreteded scripts. How this is done is explained on the web by the author of the tool, a well known author of programming books. It would be nice if you could get FB to run C# scripts in this way. Having access to the .NET framework in this way would give us easy access to lots of really powerful functionality, which I believe would make FB scripting a whole lot easier.
Inno Setup is a popular high quality tool that uses Pascal Script from RemObjects, freely available with source. In Inno Setup you can set breakpoints. It would be nice to have this Delphi like language in FB.