Maybe passion is too strong of a word, but interest I would say definitely. I wouldn’t want to work somewhere or on something I’m not interested in. I also wouldn’t want to work with people who have no interest in what we are working on. You would be surprised how many people have ZERO questions or knowledge about the project when interviewing. Honestly a simple 5 minute Google search would be good even.
That’s the key. A candidate with 5 minutes of Google search will make it over who doesn’t. If candidate performs well technically and comes across as good team player then that should be sufficient. Interest/passion about Siri before working on it is worthless parameter.
Happened to me as well, Apple Siri was the easiest interview I had and my interviews went really well. I think I didn't care to learn enough about Siri. I hope you had/have better luck at other places. I was lucky to get some offers from other good companies.