To follow up on that, when did 40 oz malt become a 'lesser mans' drink in so much as people think drunks, hobos or college kids are the only ones drinking them for the most part?

This article seems to answer most of the questions.

The guy who wrote the article supposedly owns the largest collection of 40's bottles in the world. In short, it was invented as the next logical step from the 32oz being 25% larger. It was first started in 1959 or 1961 and was popularized largely due to Billy Dee Williams (Lando in Star Wars) who endorsed Colt 45. This seems to have started the trend of being marketed to African Americans and was further popularized by the early 90's rappers.

I know that these used to be called GIQs (short for Giant Imperial Quarts), at least in New England. Narragansett Ale used to be sold this way. I don't know if this was all over the US, or just in New England. I also don't know when or how 40 oz became the preferred nomenclature.

I could speculate, but this comment is already probably insufficiently sourced or notable for the subreddit. If a mod wants to delete it, I won't complain. But OP, you might want to look into the history of the GIQ.

EDIT: You might be interested in this essay, which I just remembered I read a few years back: http://faithfulreaders.com/2012/04/29/malt-liquor-a-history/