Being able to decrease the visual indent (either by using actual spaces of 2 or 3, or by using a tab that takes up less space) is one of the more important features of a text editor or note app for me. I often organize notes, ideas, reference information, etc, using multiple levels of indentation (typically no more than 4), but having 4 spaces for each level means that there is very little horizontal space left for the content at deeper levels.