A lot of knowledge and truth can be quite disappointing. I do think shielding oneself from truths and knowledge probably would make someone more happy. Think about it - do you think you would be more happy knowing the darkest thoughts and actions of those around you? Of those close to you? What if your spouse was having thoughts of leaving you? Would that make you more happy or less happy? I suppose you could say that if you were privy to their thoughts, you might discover that they love you and think about you more than you imagined, so that may be a net benefit, but I think we humans have a tendency to focus on the negative, and so an abundance of information leads us to focus on the negative things within the information, which makes us less happy.