I feel why there are no much speculation about Madrid against Salzburg is because Salzburg should be more easier for Madrid to win and also get a good the position as the make way for themselves to participate in the next stage of the competition compared to that of Manchester city against PSG. PSG won't be an easy opponent but I seem to trust Pep's strategy more compared to that of Luis Enrique.
Since Salzburg will be traveling to Santiago Bernabéu. Madrid will use their home advantage to take good dominance.
If we compare the two matches, the Man City and PSG match is indeed a more important match. But this is a tight competition and even weak teams can provide surprises such as draws.
Indeed, on paper Madrid should have an easier time winning, but to be honest I'm worried that Salzburg will give Madrid a hard time. My prediction is that Madrid might be able to get a winning score in the second half.
And regarding Man City and PSG, I agree with your opinion that Man City has a greater chance of getting full points in the match.