I guess his main positive for you is his ability with his feet?
He's also a good shot stopper, but yes, he makes sure that there is little use for opponents to press high, Barcelona can usually control their own buildup because of the keeper. This is a bigger effect than if he stops 50% or 60% of a certain type of shot, it influences the teams entire style and how they can be set up both with and without the ball.
I think his style annoys a lot of people. Evidently it does, it's alot of moaning about his facial expressions, that he screams too little etc. But also his playing style, he is usually not diving for the ball or attacking the attacker, but rather positioning himself in a good spot and covering. In my video he saves a lot of 1v1:s, but it's easy to see these saves just as misses by the attacker...
Just because I write a sentence saying x, y or z it doesn't mean I don't also think of several other things. Do you think my opinion is only the exact things I write? If so that's utterly bizarre. Roberto was very good for a few years. He's been trusted based on that and ALSO due to poor recruitment and ALSO PARTIALLY living off reputation as a la masia player and that goal.
I just think that goal is a peripheral thing, and that users here should not care too much about it or assume that he is living off of that goal in the minds of anyone making decisions for FC Barcelona. I even doubt there are any fans thinking Roberto should be judged more highly because of that goal, but I've seen a lot of posters pointing towards that goal in the same way you did, almost making it a negative thing in a strawman or demon-like way.
Yes he is a la masia player who can play a lot of positions and who mostly does well, he never had potential for more than a squad player which also made some people underrate him after they found that out...