In Thor, we see Loki saying to Thor that if he destroys the bridge then he won't be able to see Jane again. It is further confirmed in The Avengers that Odin had to use dark magic to send Thor to Earth.
But in Thor: Ragnarok, we see Thor planning to visit Earth with all the residents of Asgard, and they plan to do that by ship. Then, in previous movies, why couldn't Thor just have taken a spaceship to visit Earth?
I calculated the time it would take to reach Earth and it's barely a day, as shown in Avengers: Infinity War (as in, the same day Thor's ship destroyed by Thanos, then Guardians reached that location, Guardians came to Titan following that, and Tony and Strange also reached Titan the same day).
So, what was that fuss about the Bifrost and dark magic in Avengers?