It appears so, assuming that is what a state of non-existence feels like and maybe, death itself has much less to do with a state of sheer nothingness, and more to do with a state of neutrality and partial (neutral) awareness, as that which I had experienced.
However I wonder how many people, envying those who have an ignorant happy bliss (if this is your defintion of "happy") would actually want their child to be born as one of these imbeciles? Another thing is that there must be some forms of brain damage you could do that could put yourself into that kind of state. You would really want that, honestly?
Some guy I worked with actually wished he had brain damage for all of the above reasons ..but as you later mention, intelligence isn't necessarily the problem here, or at least not completely ..as I'm sure there are a number of blissfully intelligent people still walking this planet.
I do think however, a lot of unlearning needs to take place if one truly seeks happiness in such a world as ours. Strangely enough, one might agree that our tendency towards being excessively self-conscious (ie., more aware of who we think we are) is what makes us more unhappy ..and to what many have mentioned, perhaps you have to lose some of who you think you are in some manor, if you truly wish to live in peace.
As Jan mentions above .. I do agree simplicity and realistic goals, contribute much to our level of satisfaction.
