I think they have always had dueling aspirations between making the best music they can and making music that is incredibly popular. On No Line, it's pretty clear that they were largely focusing on the former, what with the globetrotting recording sessions and the songs they came up for the first four and last four songs of the album (plus the ones you mentioned). I also think "Every Breaking Wave" dates back, in some form, to around that time too. But then at some point, they definitely had the "We need to write another 'Vertigo'!" And that's how we got "Boots."