If you're actually writing code from scratch in a linear fashion, then you do spend a fair bit of your time in insert mode. After a few years of vim use (about four years, so I'm not a grizzled veteran by any means), I've found that when I'm writing new code, I do use insert mode more often than usual.
But the difference is that when I need to make some edits to the code I'm writing, I immediately swap back to normal mode. It's not something you notice much if you don't use vi(m) a lot, but you go back and edit the code you're writing quite a bit.
From my experience with vim, this guy is spot on: someone who has really used vim for a long time will spend a majority of their time in normal mode, because literally you don't do anything in insert mode except write text in a linear fashion. If you want to move your cursor somewhere else, you go into normal mode to move it. If you want to erase a string you just typed, you go into normal mode. If you want to refactor your if statement into something cleaner, you go to normal mode. And the list goes on; normal mode, once you've learned it, is just so much more fluid that you will want to be in normal mode 99% of the time.
Vim can be a little crazy to use, yeah. But once you have learned it, it's unconscious. It reminds me a bit of algebra. When you first learn algebra, you're really focused on the symbolic manipulation. But as you get into the higher maths and have more experience, you'll find yourself rearranging equations without any thought. Vim is the same way, and that is what makes us vim users addicted to it: complicated text editing becomes subliminal.