I've thought about this for a while and I'm not sure what to say. I don't think I'd go so far as to say that reading any single book "revolutionized my entire life", I just got useful information and perspectives from them. I think that your guess is at least partially right, that some of the people who have the strongest enthusiasm are probably ones who haven't read much philosophy before and therefore are getting more groundwork covered in reading State and Rev [or whatever] than you and I did, because a fair amount of that stuff was already familiar to us.

Reading theory generally shouldn't be revelatory in some grand sense, this isn't a religious text and you aren't supposed to fall into some kind of transcendental rhapsody, you're just developing your understanding point by point.