Why is the narrator of "Free fallin'" by Tom Petty free falling?
Yeah I'm free, free fallin'
Why is the narrator "free falling"?
Does "free falling" imply some form of destructive freedom or loss of control?
The phrase 'free-falling' does more than imply a loss of control. It denotes it; specifically, in literal use, the absence of "check or restraint" and "propulsion or drag" (OED). Figurative uses draw on those literal senses, and so also on the loss of any control afforded by check, restraint, propulsion or drag.
Whether the phrase implies "some form of destructive freedom" (OP) is another question. The state (of being 'free-falling', of being 'in free fall') is not inherently destructive, but is inherently free (of restraint, etc., as mentioned); it is the cessation of the state that may or may not be destructive. Yet the state may, sans context suggestive otherwise, as likely as destructive things, end in bliss, or pleasure, or any of a spectrum of desirable things.
Absent suggestive context, 'free-falling' does not necessarily imply "destructive freedom".