And some aircraft that become almost universally loved start off as white elephants. Take the Hunter F.1, for example: engine surge issues, particularly when firing the cannon, no airbrake, cannon shell casings damaging the fuselage, and the very poor range which led to the infamous incident of six aircraft lost on the same flight. Thankfully they persevered.
On the subject of the Defiant, 37 were shot down by the Luftwaffe in air combat, while it scored 152 kills in return. Time, maybe, for a reappraisal?