No, the MacBook did not switch to a single USB-C port simply to sell dongles. That really makes no sense at all. Dongles are not a major revenue source for Apple. And Apple's never shipped HDMI adaptors with their products, or DVI adaptors, or anything like that. Most people don't need them. And the new USB-C Macbook isn't the first computer that would need an HDMI dongle; I think the Mac Mini is the only computer Apple has shipped with an HDMI port in a long time. It seems kind of absurd here that you're claiming the move to USB-C is somehow Tim Cook being greedy, even though one of the most common complaints about Apple is how they're using Lightning instead of USB-C. Either USB-C is a good idea or it's a bad one, you can't have it both ways. And if they didn't remove ports from the MacBook, it would still have Mini DisplayPort rather than HDMI.

Also, FWIW, I just checked Monoprice and the HDMI dongle costs $35. And Apple's own dongle (which is $79) includes more than just HDMI (it has a USB port as well, and a USB-C charging port).