I think it is worth the extra complexity to avoid having to write \section and \emph all the time, and to make your notes more readable as a .TXT files. Also I find it easier to just set up a basic document, for markdown you can just open a new text file and start writing, for Latex you have to do a lot of setup at the start of the document to define your margins and import packages. Its not going to work well if you want a perfectly formatted document, but if you want to write simple notes styled with CSS it is much nicer to work with.