Trying to be as objective as possible:
At the time of her recruitment, Pat was dealing with the Alzheimer's issue and that may have caused DD to take a serious pause. So what does she do? Becomes instrumental in assembling one terrific freshman class at UNC - her, Mavunga, Gray, and Washington. Then she promptly bails on her teammates after 1 year, leaving them flying in the wind. Ultimately all of them left UNC, but she went to Tennessee, where supposedly her heart always was.
Almost immediately after her decision to transfer to Tenn, Cooper announces she's going there - a top 20 kid who many Tenn fans thought was a top 5 kid, and was great friends with DD.
She has flashes of brilliance while at Tenn, punctuated by lazy and disinterested play on the court. Her attitude and demeanor was not one of a hard working kid trying to do her best, but rather a surly, spoiled kid who could play any damn way she choose since the coaches would never hold her accountable. I think it was mostly that attitude over the past 2 years that helped cause people to sour even more on her. Add to it a WAY overly involved father who publicly called out Holly on twitter after a loss saying something like "of course you are going to lose when you don't put your best player in the game".
LVol fans who claimed to "know" the real DD said she was a wonderful person. I don't know about that. Breanna Stewart, twice the player DD was in college, signed her LOI on the hood of her car. She's a sweetheart to her core. THAT is a wonderful person and UConn is chock full of kids like that.
Anyway flash forward to this year and Cooper, the PG of the future, leaves the team apparently after instigating a fight with Jaime Nared.
Meanwhile, instead of choosing to leave and enter the draft, DD publicly comes out saying she's committed to her senior year and decides to stay in college (also says she wants to mentor the great freshman class Holly recruited). Not 2 months later, she chooses to leave school for a "professional career". Where - on Mars? She can't enter the WNBA now but I suppose she could go play in China or Turkey or some other country after the WNBA season is up... If that was ALL she did, it might not make so many people turn on her, but she has a history of being a selfish person and player as evidenced by all her actions over the years. If I had to guess, I'd say that's mostly why people aren't sympathetic to her.