You are assuming that the programmer's personal desired reflect what is best for humans as whole. Relying on what humans think that is rather than a top-down approach will likely work better. Moreover, many people see an intrinsic value in some form of democratic approach. Thus, even if I could program a super-smart AI to push through my personal notion of "good" I wouldn't want to because I'd rather let collective decision making occur than impose my view on everyone.

This is aside from other issues like the fact that there likely won't be a single programmer for such an AI but rather a host of people working on it.

A lot of these issues are discussed in much more detail in the sequences and older posts. You might be downvoted less if you read more of those instead of rehashing issues that have been discussed previously. At least if you read those, you'll know what arguments have been made before and which have not been brought up. Many online communities one can easily jump into without reading much of their recommended reading. Unfortunately, that's not the case for Less Wrong.