Yes, you can't please all the people all the time, that's true. However, just one extra level would add a great deal of extra flexibility for a large number of people. I see so many people asking for this feature. It doesn't make sense as a company for them not to want to implement it. However, we'll never know if this is something EN is working on until we get it or don't.
I for one would just like to see "Dividers" or "Sections" (sub-notebooks), that would only add one extra layer but it would make my life so much more organized. That would make the hierarchy as such: Stacks>Notebooks>Divider or Section>Notes. This would be in line with the whole notebook analogy that Evernote has created. Notebooks often come in multiple subjects with dividers in them for different topics within the same notebook. I think added this sub-notebook level makes perfect sense.
Tags don't seem to work for my brain. I use them, but in the traditional way they were originally designed for, as a way to add to the organization of things. Not as the main focus for organization. For me and the way I think, Tags are too cumbersome to organize and access. Searching and then narrowing said search by tag feels like way too much work or remembering search complex syntaxes just to find one note. If I put certain things in a designated folder, I can just go straight to that folder and know it'll always be in there. It's very straight forward type organization. Again to each their own but if there are enough people that want a feature and it is withing their power to add that feature, why not add it.