Well, that's the problem with electing governors as presidents.
The federal government and the state governments are supposed to have different realms of authority. Being a governor doesn't really prepare someone to be president. It does tend to give us big government presidents that use the power of the federal government to address issues that are supposed to be dealt with by the state and over which the federal government has no constitutional authority.
It's not a red herring. Bush's foreign policy has been highly influenced by others on his administration because Bush didn't have the experience to form his own policies. We really couldn't tell much about how Bush would deal with foreign policy issues until he appointed his staff, and his policy often seems inconsistent due to being sometimes greatly influenced by close advisers he brought with him, and sometimes mostly influenced by career diplomats in the State Department.
You make some valid points, but the qualified foreign policy expert seeking the office of president is a rarity. Governors are the closest thing to presidents despite the negative results you point out. And governors are extremely popular candidates if recent elections are any indication.
As for foreign policy, all the voter can rely on is the campaign rhetoric and judgment of the candidate to surround himself with able people. But it will always be a crapshoot for the voter, as even the president cannot control world events.