A much better direction, IMHO, is to simply use plain text.
That said, plain text with a simple markup language such as Markdown might be the way to go.
It is clear that Evernote does not go the "plain text" direction. And with reason: one of the strengths of Evernote is exactly that it can handle rich text and images.There are much better solutions for dealing with plain text notes anyway (simplenote, etc.), some already supporting Markdown.
It's much easier to simply paste the text into a good word processor or html editor and apply styles there depending on the end use.
For the scenarios where I use Evernote (especially meeting notes), Evernote is the "end use".
IMO, the point of having styles in Evernote would be to be able to quickly make text parts look like something specific (say, a section title, or an important warning paragraph). This currently requires numerous clicks (e.g. to have blue headings this would be something like: select text, make bold, increase font size and set font color).
Styles would allow to do the above example in one or two clicks, or (even better) using a customizable keyboard shortcut.