There are newer law review articles but none quite so comprehensive and earnest as Cass R. Sunstein & Lawrence Lessig, "The President and the Administration," 94 Columbia Law Review 1 (1994), https://chicagounbound.uchicago.edu/journal_articles/7779/
That's the same Lawrence Lessig who fought (and lost) copyright extension. 1994 is long before tribal politics became as pervasive and extreme in academia as it is today (not that it didn't exist back then). The paper pulls its punches and assumes unitary executive proponents are arguing in good faith, rather than rationalizing a foregone conclusion.
And while I agree we don’t want the DoJ treated that way, that’s how it’s been operated since its beginnings! If anything the past few decades have been relatively not so bad. And regardless of what I want that doesn’t answer whether it would be within Congresses power to make it independent of the President.
To whom? The U.S. Constitution says that Congress has the power
"To make all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers, and all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof."
That's rather clear.
The legislative branch makes those laws and the executive branch executes them. Beyond that its role is limited ... commander-in-chief of the military, pardon power, making treaties (with approval of the legislature), appointing ambassadors, judges, and other officers (with approval of the legislature).
The legislature creates (or removes) the departments and sets forth their duties. The role of the executive is to see to it that the departments carry out those duties as established by the legislature.
The best distillation of our current conundrum I've heard is that our framers architected a system where the branches of government would compete (i.e. protect their power) against each other. Today, we have people in each branch willing to forego their own branch's power in exchange for greater party power.