FWIW, I don't think Harvard Extension School is a good example of this trend. It was founded in 1910 with a fairly egalitarian ideal to serve the people of Boston. Not quite a latter day cash-in.

I retook Calc I through the extension school six or seven years ago out of curiosity when I was considering doing an online Master's. Rigor was on par with my undergrad Calc I or perhaps a little higher and the quality of instruction was definitely higher. The lecturer (Eric Towne!) had a command of the people and history surrounding the concepts he was teaching and shared lots of fascinating context.