If your worldbuilding has no rules or limitations, there are no stakes.
If there are no stakes, there can be no "heroics" or struggle since you've basically created a universe where there are no rules and the fantastical is normal. Your characters can only be as heroic as the problems they have to overcome, and if those problems can be overcome easily because there are no rules or limitations then there's nothing "great" about what they're doing.
For me, the reason Search For Spock works as a story is because for the characters there are limitations, sacrifices, and consequences. If you eliminate those elements from the story and say the circumstances will be whatever we imagine them to be for the moment, it robs the story of any depth.