By your logic, same with the Death Star in ANH’s crawl (not considering the prequels or Rogue One). And “I am your father” was just dropped on the audience as well.
The Death Star is a completely different beast. It’s the opening crawl for the first ever movie in the saga, where audience has not previous conceptions about the lore or the story. Of course you’d need to establish the crucial foundations to ANH’s plot: there’s a cruel Empire, they have a planet-killing Death Star, and there is a rebellion seeking a way to destroy it.
Now imagine if the crawl for Empire stated that Darth Vader wanted to find Luke suspecting that he’s his son.
and the rushed pacing of TROS doesn’t make matters better.
I’ve watched TRoS TWICE, and I never understood how the pacing is rushed, exactly.
Just compare the opening fifteen minutes to the prologue of any other Star Wars movie. TROS crammed three complete different scenes, each with its own significant contribution to the plot, in a time span equivalent to the entire opening of TFA on Jakku. There’s barely any room for scenes to breathe until, like, the beginning of the second act.
Except the characters DO react to Palpatine’s return. “The message CONFIRMS the worst.” Implying the Resistance DIDN’T believe Palpatine was alive at first. Then they’re surprised, afterwards asking all sorts of questions.
Also, Kylo Ren wanting to kill Palpatine IS his reaction. He is a threat to Ren’s power, and he’ll (referring to Ren) do whatever it takes to take over the galaxy for himself.
Yes they were skeptical, but the actual transmission from Palpatine (which itself is a questionable plot element but that’s for another debate) was received offscreen. It’s like if Luke found out about his parentage in the meantime between Empire and Return of the Jedi, with this revelation stated in the ROTJ crawl, and we only see Luke’s reaction to Yoda confirming that he is Vader’s son.