I had the exact frustration too. here is the issue I've submitted for this matter:
https://github.com/dendronhq/dendron/issues/481
as stated in the thread, keybindings are a bit tricky in a platform where a lot of things are happening. If you have any ideas on what keybindings would be a good default feel free to comment. If we can come up with a better default for the particular commands, it will be an easy thing to change, but to have a cohesive set of keybindings as a whole we might have to have more discussions on this matter.