Pac-Man was also the biggest game in the world when that awful cart came out. The maze was different, the colors were different, the animations were gone, the game speed was incorrect, the orientation was wrong, the scoring was wrong, and one of the objects (fruit vs. vitamin) was wrong.
Personally, I was of the age where it was the first awful game that I recognized as awful. The concept of a crappy video game hadn't really hit me till I played that.
I think E.T. gets a bit of a bad rap - a guy had six weeks and made a somewhat-interesting puzzle game out of source material that didn't lend itself to a platform built for action games. But Pac-Man for the 2600 is an abomination. (There were also Pac-family games developed later that looked great on the 2600, but I've yet to see a good E.T. game anywhere, heh.)