Usability vs complexity (notepad vs vi)

I like to use apps that are easy to use.  One of the things that we all love about www.google.com is  that it's dirt simple.

However, I also like to use applications whose user interfaces are complex.  For example, instead of the relatively simple text editor notepad, I often favor a program call vi.  For those who don't know what vi is, it's a text editor, that I can hardly begin to describe.  Here are some seemingly ridiculous features that probably sound like a foreign language to the uninitiated:

• There is a text insertion mode and a navigation mode.  If you press the character 'd' and then 'w', in one mode, you will see the characters 'dw' on the screen. In the other mode, you will delete a word.
• There are things called folds.  If you create them, or have them created based on the text, you can quickly hide and show blocks of texts.
• There is something called marks, which you can set.  You can them jump from one mark to another with just a few keystrokes (instead of pressing down or page down a hundred times).   
• You can take advantage of other tools and do lots of other magic like text replacement with regular expressions.  

In order to use complex tools like vi, you need to read, practice and spend time looking up reference sheets.  So why go through the pain?  It's a trade-off.  Using a tool like vi enables me to do powerful things that save me time.

So, what is the right level of complexity versus usability? I guess it depends on the application.

Well, then again, maybe usability doesn't matter all that much.