In GF2 hyman roth is in a deleted scene with young clemenza and young don corleone.

Wouldnt it have made sense to keep that scene in the final cut to give us the audience a sense of history between roth and the corleones?

Although the plot is one of the best in film history, roth would be considered even more dastardly if we knew more of their history.

You make a good point. However maybe by leaving it out it shows that the'r "partnership" wasnt as good as it seemed when Roth talked about it. We already know Vito didnt trust Roth

It would have provided some context, earlier in II, when Pentangeli says to Michael, "Your father did business with Hyman Roth, your fatherrespected Hyman Roth, but your father never trusted Hyman Roth..." Other than that, it's not a serious omission.

You may have noticed that, in the deleted scene, Vito looks to be about 28 - 30 years old, Roth looks to be about 17 -18. But, in Cuba, Roth's birthday cake icing says "Happy 67th Birthday." That would give him a birth year of 1891, making him only about a year younger than Vito.

Over the years we've posted almost endlessly about what scenes should have been included in the theatrical release of the film. There's a bevy of them (some of dubious entertainment and informative value). At 3 hrs and 20 mins, even the most ardent fans of II would have been challenged to avoid restiveness during a longer film.

Reminds me of a scene in the Beatles Anthology documentary in which Paul talks about the White Album.
He says that there was a lot of hindsight as far as what was included and what was not. The best line is when he says "It was a good album,it sold well,it's the bloody Beatles White album,shut up."