"But I find their contribution to home consoles is overrated, at least from a software point of view. Nearly all Atari's best 2600 games are arcade ports. Adventure and Yar's Revenge are like the only Atari games (not including Activision's stuff) I can think of that were both quite good and were not arcade ports."
You need to remeber, that back in those days (my days) arcades were the big thing. To be able to play "arcade" games at home was the biggest thrill in the world. No body wanted games that werent in the arcades. Add in the fact that development houses were kind of scarce
, and the need for original console only games wasnt really needed.
What Atari did, IMO, that was so amazing, was that they, with one machine, made kids stay home. Nothing since the TV itself had accomplished that feat.