I didn't mean that much by it, but I have a bit of thing about those occasions when an author or songwriter says something and people understand the opposite. The point of John of Gaunt's speech is "you may think it is like that, but it is actually like this". You get the same thing in West Side Story where a lot of people think the song is about how wonderful America is, but is actually about the gap between the American dream and what the immigrants experience.

No need to dwell on the point any further.