Even though I love drawing and doodling, and it seems that my brain works better when my pages are colourful and fun, I admit that I don't always have the time (or the mood) to be creative. During those days I want my bullet journal to be simple and functional.
I've also read lots of times in the bullet journal community, comments from people who don't want or they just can't draw or sketch, and generally they are not into creating fancy and complicated pages. And that's perfectly fine. Each person is different and that is the beauty of bullet journaling - to personalise your journal in any way you want and to adjust it to your needs and wants.