Career civil servants perform a very different role. They implement policy, rather than make it. They provide continuity and specialized expertise based on institutional knowledge and experience. Traditionally, at least, many spend their entire working careers in government, although that is changing. These roles are separate, and it's important to do all we can to keep them separate.
Most political appointees understand the temporary nature of their role quite well.
But in some ways, we seem to go out of our way to tempt them to stick around. People who hold political appointments should not be allowed to compete for career positions until a new Administration has taken office. And I think it goes without saying that White House officials should no longer have a Ramspeck-like opportunity for automatic conversion to career jobs. A factor that has long reinforced the temptation for some political appointees to stick around is the structure of the federal retirement system, and establishing a portable retirement system for them, involving individual 401K-type accounts, would be an important step. Frankly, though, I would strongly recommend moving to a system of individually-owned retirement accounts for all federal employees, political or career.