I agree, and I would like this as well. An option would be to have an entry in the keyboard shortcuts for it, so a "select all lowest notes" and "select all highest notes". The advantage of that would be that we can then create very handy macros where we can delete all lowest notes with one command for example.
But please, make the whole request shorter, you can't expect anyone to read through all of it. That may cause less people to vote this up.