Well, maybe not forgotten as such, but if I had to pick one decade, I'd pick the 70s. And I don't think it's anything to do with garagiste success with the DFV, because what engine is in a car isn't the memorable thing about a season. When you look back at the period post Stewart I also think that there is a slight lack of drivers that are now considered to be all-time greats. Obviously you have Lauda (and Fittipaldi etc.) but most periods have at least one driver who is generally rated above Lauda on all-time lists. For a best driver of an era (if you consider him the best anyway), he's probably one of the lowest rated, if that makes sense.
Which is unfair imo, Lauda was a brilliant driver. His only problem was that outside Italy he was generally loathed for his utterly ruthless and robotic character. In addition, the Hunt-Lauda rivalry exacerbated this image in the Anglophone press which is arguably why he is regarded less in the UK.