That's how I feel, I like watching trailers, but then I don't feel the need to actually watch a movie. Back when I had more free time I would watch 50 random trailers instead of going to cinema...
A good movie will entertain even when you know the plot. Certainly nobody goes to see Shakespeare for the "twists".
Some movies spoil themselves by putting all of the good things in the trailer. The problem isn't with the trailer, but with the fact that they only had two minutes worth of movie to make, and should only have made a two-minute-long movie.
Miyazaki films are worth watching many times, for their beauty alone. The stories, too, reward re-watching because they are a journey you get to take with characters you connect to.
I wouldn't presume to doubt their marketing acumen. I assume they know what they're doing. But if they believe that I would see a trailer and not want to see more, then they seem to think less of this movie than I have come to expect from Miyazaki.
But there are also plenty of ok movies that are fun, but mot rewatchable. I usually enjoy a movie more if I watch it without knowing much and getting surprised.
I think there are only a handful of exceptions. Ironically, the first exception that comes to my mind is Miyazaki's own My Neighbor Totoro.
That is something that watching trailers robs you of. Even for fantastic movies, that’s something you’ll never get to experience no matter how many times it’s watched.
Plenty of good trailers that simply say hey this movie's got a cool aesthetic.