While ignorance may be bliss, people who are ignorant are out of touch with the world around them. This can cost them friendships, relationships, and even their job and economic circumstances. Still, they may not even know what they are missing out on, and that may be the saddest part of it all.
I would rather be aware of myself and my surroundings, even if this means I am relatively unhappy compared to those around me. What good is being a joyful simpleton if this means you are not in touch with reality. Reality is all about the accuracy of your ideas vs. the world, otherwise you are just living in your own head.
If you don't care about anything, and because you don't care about all the wars and famine and crime and poverty you are a happy person, where does that get you? Jobs won't hire you just because you're happy. If you're constantly worried but you're qualified, you have a better chance of getting hired than a happy idiot. Ignorance gets you nowhere in life. Genius does, even at the cost of happiness.
As a worried genius, I would say no it's not better. Curiosity brings about enlightenment. Past enlightenment you get confusion. A genius can bring about change but that is also based on ignorance. Even curing world hunger can not end suffering. People try to fix the world, but no mortal can achieve that. To believe that you can only adds to your own blissful ignorance. Which in the end leads you back to being a "smart" joyful simpleton. Then the question really becomes; Which is better, a sheep blissfully unaware of its impending death or a sheep fully aware but unable to change its fate? Neither one sounds like a life worth living.
It is better to be a joyous simpleton because life is short and worth enjoying. If you aren't a genius, you will never know what you are missing; you will simply go on living your happy life. I, for one would love to live a joyful life everyday with my family.
It's hard to say that one is better than the other, because the human experience is so varied. You can be a joyful simpleton who lacks the skills to socialize, but if you have people around you who care and understand your condition, your life will be enriched. On the other hand a worried genius seems just as likely to drive people away or be poor at socialization. Because people (and their circumstances) are so different I have to say "no".