Honestly, the only people who say it's perfect are biased hardcore nintendo fans who haven't played any other games of the genre to make an objective opinion.
You think is all about nostalgia? yeah, it could be a part of it, but it's not all.
OoT was a revolutionary game for it's time, no matter if you looked at other games, or even other consoles, it was a perfect execution of all the things a videogame have to had to make it an instant classic. And it's an accepted fact of the industry of videogames. Not just the opinion of nostalgic fans.
Skyward at the other side, it's an ok-fun game, but does not reach that level of a classic for these times that are running. It's what people fail to understand when they try to compare 2 games with an age difference of more than 10 years, you have to take everything to count, the context, the time, the way the games were played.
Not just,"oh OoT is old and Skyward is new, so now Skywartd is better."