I was a budding adolescent when I saw Cooper first on TV (Top of the Pops) with this vid here, I'd have to lie if I wouldn't admit that I was completely mesmerized by his look. Ignore the music which is not original (but a credible tribute), I couldn't find an original TOTP performance that plays in Germany:
When I dug a little deeper and heard the rumours in school that "Alice Cooper kills chickens on stage"
(he never did, well just one, but that was an unfortunate accident as the chicken refused to fly when he threw it back into the audience - from where it had come too; young Vince had missed a lot of biology class which also probably explains that gender uncertainty evidenced by his later stage name)that only added to the fascination.
Over time though, you're right, the image probably drove more people away than it initially attracted.
My first rock album ever was - no, not Deep Purple, that was my 2nd, 3rd, 4th and 5th - Alice Cooper's Greatest Hits. I
adored loved (it) to death that album and its wonderful sleeve,
thought every single track brilliant. Still know it by heart today. The pun inherent to the "greatest hits" title on one hand and the mob style cover on the other only dawned on me decades later though!