I heard that Capablanca never liked to bother with openings, would never study chess or read books. Despite all this, he became world champion. Is this an exception to the rule? Have times changed today were players are too strong and study is mandatory?
Capablanca didn't like to "study chess or openings" means that he didn't like to study formal chess (as it was understood in his time).
On the other hand, he studied more, and had a better grasp of chess principles, particularly as they related to the middle and end game. His best exposition of this was "Chess Fundamentals."
Because he focused on principles, rather than "book" moves, he was the hardest person in the world to surprise with a new line. He beat back the Marshall Attack that Marshall had reserved especially for him.
Nowadays, there is more and better book knowledge, so it's helpful to learn some of it. And the other reason is that not many players have the instinctive grasp of the game that Capablanca had.
One can have a natural talent for the skills inherent in chess, such as spatial relations and pattern recognition, but without knowing some of the basic principles of chess, most easily obtained through study, it's difficult to see how one could become truly great. Capablanca was supposedly such a natural talent, particularly in endings, but even he found it necessary to study openings when he reached the higher echelons of chess in order to continue to compete successfully. Other natural talents such as Reshevsky found the same to be true.
In those days, people do not have to reckon with tactics and preparation at the level of silicon beings, they just need to play better than the other guy. If Capablanca were still alive today, he would be crushed by most elite players because general principles do not stand up to tactical refutations, especially if they came from the computer.