1. While I "get" the big picture executive power point about the president having ultimate authority over his ministers, and ultimately that's the controlling legal principle, the FBI director (and, probably the fed director and other independent agency commissioners) who are confirmed by the Senate for a term of years reflect a judgment that certain offices do have a bit more 'independence' in their tenure. Not as much as the lifetime of scotus justices, but more than your average agency appointee serving at the pleasure of the president.
2. The FBI has a unique history which, once that asshole J. Edgar finally kicked the bucket, Congress corrected with a careful balance -- extended tenure to assure some level independence and continuity of policy in a really critical law enforcement position, but finite duration to prevent ...well, J. Edgar II.
3. For my money, both of those values are important, and should be retained short of cause-based malfeasance. I don't think we want the chief law enforcement officer in the country to be "more" political, particularly given the incredibly broad powers they wield and the increasingly blurred lines between criminal and civil investigations.
4. Now I get the objection that Wray and his ilk have "already" acted politically, but honestly, I'm kind of unmoved with that sort of "opportunistic whataboutism". I'm sure they have to a degree - as I've said elsewhere, those guys that are at the second or third tier of DOJ/FBI and aren't necessarily political appointees have a tendency to think they run the place (and the country), and having met my share of them at the home office, there is an archetype that you have to watch out for. But while there are always abuses of political nature, that's actually a feature rather than a bug.
