I suspect they find them to be confident, exciting, unpredictable, passionate, challenging, strong willed...etc Some women probably feel having to "earn" or "compete" with other women for a "bad boy's love" (makes it more valuable) than being given love "freely" from a "nice guy". These are the same women who live according to the quote;
"We ignore those who adore us and adore those who ignore us."
I imagine there are others who mistake "drama" for love. A lot of women just find "nice guys" to be too boring, too nice, or see them as being weak. They avoid them to keep from hurting them.
Having said all of the above from my observations it appears most of these women eventually outgrow the "bad boy phase" as they get older and become more practical about life. This has probably contributed to such clichés as "Nice guys finish last" or "Bad boys have all the fun and nice guys get the left-overs".
Thankfully there are over 7 billion people living on this planet, which means there is someone for everyone!