Do DC-DC boost converters that accept a wide voltage range always require feedback to maintain constant output voltage?
Essentially, yes. Even if the input voltage is fixed, feedback is still required due to component tolerance variations and changing output current load - regulation would be poor without some form of feedback.

Isolated DC-DC (or AC-DC) converters such as the flyback topology can make it inconvenient to implement feedback, since traditionally the feedback signal would have to cross the isolation barrier. This can be done with optoisolators, but primary-side sensing is also an option, to cut down on part counts at the expense of a little load regulation (which can be made up by an output linear regulator)