My guess that this lower resolution text was an idea by Evernote to provide a preview quality version, which when you find the note you want to work on, you open it and it renders correctly. Perhaps they thought it would make the storage of notes more efficient. Just a guess.
Anyway, I have the same issue as everyone else, it isn't good, but at least I can take the strain of my eyes by opening up the note I'm interested in... not ideal, but not really a disaster. A very First World problem really, but it would definitely be nice to see it fixed.