Why do people have such large trailers?

I agree with 4x4Dodger's comment. I think that since the 80s, people are more susceptible to advertising and the advertising ploys are more sophisticated. I don't think manufacturers are building bigger because people wanted bigger - I think many people are buying bigger because they believe the marketing that bigger is better.

I also think that we have gotten spoiled about "personal space" and we have a much harder time sharing our stuff.