>That is not a benefit for an intelligent individual. It is a benefit for society.

Living in a society benefits an individual. That's how societies formed in the first place, organizations of individuals who work together survive better than individuals who live on their own. A benefit for society is therefore a benefit for the individuals who live in it.

>And this restricts your options for acting in ways that may very well prevent you from increasing your happiness.

I think your logic may be flawed here. If I behave in a way that makes me unhappy, your solution to increase my happiness is not to stop that behavior, but rather psychologically condition myself so that the behavior makes me happy instead. That would be like if you told me you broke your leg and it made you unhappy, so my solution was to tell you to just condition yourself to enjoy breaking your leg. After all, if you don't enjoy breaking your leg, you're just restricting yourself from increasing your happiness. Now I don't deny that it may be theoretically possible to condition yourself to enjoy breaking your leg, but I would argue that it would be unpleasant, nearly impossible, and bad for your physical well-being to boot.

Now you may argue that the only difference here is that immoral behavior is not physically bad for you. Well as long as you're living in a society with morals it is. If your society functions well, you benefit. If it does not function well (due to its members engaging in societally destructive behavior which we have termed "immoral" behavior,) then you do not benefit.

If you were to live outside of society, then (if not for guilt) you could engage in any "immoral" behavior you wish without any negative consequences to yourself. And in fact, people who live outside of society tend to go in this direction (pirates and such.) But this is only an increase to your overall happiness if you perceive the added benefit of being free in your actions to outweigh the benefit of living in a society. I personally believe I benefit more from living in a functional society (I can make use of doctors, grocery stores, police services, etc.) To me, those are worth more than the freedom to murder someone if I felt like it. Note we're still talking about a situation in which guilt has been abolished. As it stands, guilt is still a deterrant for me (and most people) to behave in that manner.