I think I found a decent workaround on the newer version of evernote.
I was also really annoyed about this, but I think I like my work around better than the old way. I create a password protected MS word document and then just drop that file into the evernote note where I want to keep that data. The workflow ends up being exactly the same - I click on the file attachment in evernote, it pops open a password prompt, and then I can edit my content. When I save and close the word doc, it is saved in evernote and also locked once again. AND the added benefit is that I can now use all the normal rich editing that I couldn't use before in Evernote's encrypted text area.