I would say there are two components to it. Language and project size. Java and C# where designed with IDE use in mind. I am not sure I would want to work in either without an IDE. For smaller languages like C and Python an IDE wouldn't be my first choice of tooling, the cost of using the tool just isn't worth the benefit provided. I could see switching to an IDE if the project got a little too large.
C# probably was but I suspect it wasn't a factor in the initial design of Java - I don't even remember there being any IDEs for the first couple of years of Java being widely available.
I would say that Java was designed to be used with committees. Basically a language to use if you're in a design by committee situation. IDEs were then introduced to give individuals their own "virtual design committees".
Agreed regarding C#. I've tried using vim as my C# editor, then switching to VS for builds and debugging, but I miss Intellisense too much (and with vim emulator in VS, I don't lose any of my keyboard efficiencies).
As a counterpoint, the way VS does autocomplete drives me insane. In the middle of a frenzy of flow typing, I have to move my hands away from the keyboard to the mouse to select which autocomplete entry I want. Aargh. It breaks the flow. (Although, I am using the Express edition so have not tried a vim emulator; perhaps their autocomplete is better.)
