Don't care for her writing or Bioware in general, but all those guys are going after the wrong person. If they're that upset about the way Bio has gone, they'd go after the ones who are in charge of their games, who hire the crappy writers/designers and greenlight their shit, the company's insultingly bad customer service, and their tendency to rush games out the door unfinished and nickel-and-dime with half-assed dlc.
Those guys don't give a fuck about Bioware.
What generated all this hatred towards Hepler is her unfortunate commentary on how she dislikes games, how games should be interactive movies without gameplay and her miserable "i'm a vagina that wokrs on gaem industry, envy me!" comment.
While that definitely has some to do with it and she should have held her tongue and not stoop to their level, quite a few of the tweets thrown her way seem to be blaming her entirely for the failures of Bio's last few games, even blaming her for stuff in games she didn't even work on (like Mass Effect). Even more so on that reddit witch hunt mob against her a few days back. A lot of customers are certainly growing angry at Bio, understandably so, but they're targeting the irrelevant people and by doing so attracting a lot who are only interested in trolling. When (if) they wise up and start placing the blame on the ones who really did fuck everything up, no one is going to take them seriously because of stuff like this.
The game industry teaches people that game developers are all geniuses, and that gaming keeps getting better year after year. There are no problems with this vision as long as people are satisfied with the games being released. But when a game comes out that's less than satisfactory, the cracks start to show. This is why people can so vehemently defend Bioware; they're constantly being told by the gaming media, advertising, and other fans that Bioware has great writing and their games are the best rpgs evar. When a game comes out that is definitely not a good RPG, a portion of the fanbase has this illusion shattered for them and they instantly become bitter trolls who can't stand change or don't understand Bioware's "VISION" in the eyes of the faithful.
Hepler is just the unlucky recipient of this pent up anger. Even those who have recently abandoned Bioware probably still love their earlier games (I can sympathize; I really liked BG1 and BG2 but everything they've done since then has paled in comparison). So they look for a target; a scapegoat they can blame for the decline. And then Hepler makes stupid comments about how she hates gameplay, and how anyone who doesn't love her work is either sexist or homophobic, like she's some kind of writing god and all who criticize her are heretics who should be shunned from society if not burned at the stake. I can understand the anger coming from these people.
The problem with all this anger is that Bioware won't understand where it's coming from and just dismiss it as mass trolling, as if thousands of people have nothing better to do than try to hurt their feelings. Good game developers listen to criticism; they recognize that anger has a purpose, and people are only angry because they care about the game in question. The worst reaction from fans is silence - it means they just don't care. But I digress. The devs at Bioware have surrounded themselves with a cult of faithful sycophants and any criticism is dismissed by dozens of loyal posters. Jokes about ding dong bannu aside, the worst part of that forum isn't the overzealous moderation, it's the echo chamber effect where any voice of dissent is shot down by other posters. It's demoralizing to post legitimate criticism only to be called a troll, or have all your carefully thought out points be called wrong for stupid reasons. Why even bother posting criticism when the reaction is universal? Then the disillusioned forum goer will either slip back into the fold, or flee to /v/, the Codex, or other sites where their opinion won't be so universally rejected. The Bioware forum goers probably think they're perfectly reasonable people, too; they are only sticking up for the best rpg developer evar. Bioware can do no wrong, so anyone who tries to criticize them is either mistaken or just a troll. If you think they've made a mistake, just look at all these posts by people who disagree with you!
So basically, the state of things at Bioware are the result of the game industry's masturbatory self-praise and rejection of any meaningful criticism, and Bioware won't learn anything from this because of how sheltered they've made themselves. As their games continue to decline in quality, their audience will grow smaller and their reputation with gamers will suffer. If Bioware wants to save themselves from being assimilated by EA, they need to hire some better writers, hire some community managers to assess criticism from fans, and generally work on restoring their reputation for good RPGs rather than the action/dating sims they're becoming known for. I doubt that'll happen, though.