I disagree. I think the Cup Winners Cup had more prestige at the time than the Europa League has today because the overall focus was less on the Champions League. Once they started letting 2nd/3rd/4th place teams into the CL, the prestige of any other club competition just took a lethal hit.
I think in official diction, the Cup Winners Cup actually was viewed as a 'higher ranking' trophy than the UEFA Cup because you actually had to win a domestic trophy to qualify for it. But the UEFA Cup was of course a more difficult trophy to win most of the time.