But... how many know how to do that???
How many will hack the power cord?
But I was trying to lead "mvmps" to a DIY solution with separate HDD and case, and he keept asking me about ready made solutions like Seagate FreeAgent Go and WD Passport. So I assume that he does not have the knowledge to do somethinh so advanced like this that you propose.
But Ready made 3.5" HDD comes with this philosophy... Home use.
In every case, we are talking about a car's cockpit... Not our workbench.
Safety MUST come first and all this cablemess does not guarantee that.