Yeah, that's true. It seems a must when you are accustomed to having it. But code completion is just one example. There's refactoring, debugging, and other support that a text editor can't give you which has real impact on your productivity. Even organizing your various config files and providing a UI for modifying them is a convenience.
I remember some years ago doing a contract for a large company. I insisted that I was cool with just a text editor. But the client's dev lead insisted that I get with the IDE program because they were paying me hourly and wanted max productivity.
In the end, after making the switch, I had to agree.