IDE's and Text Editors are fundamentally different tools that each have their strengths and weaknesses. Some that immediately come to mind are:
- Integrated testing
- Breakpoints/stepping through code
- Integration with other services (database views), automated class diagrams
- Large memory footprint
- Easy to extend (macros, plugins)
- Text edit functions (Ex: sublime text 2 unending keyboard shortcuts)
- Need to use another service to compile
- low support for code completion (intellisense features)
Because of the differences, one is usually the right choice over another for a certain project or language. For example: For a Asp.net web application, visual studio is probably the only choice in terms of code generation, debugging, connectivity with a SQLServer database, and version control. In a contrasting example: parsing huge log files seems more suited to a language like perl, which can be easily written in a tool like vim.
I'm sure there are many other reasons, but from experience using both, these seemed like some obvious reasons.