I strongly suspect that the Hawke hate is more a symptom of him/her not being what the Warden was to us. The Warden was the single most important person in Ferelden and decided enough to change the look and feel of the nation.
Hawke was around a lot during important times and the big choices Hawke made ultimately boiled down to whether you fight Orseno before or after fighting your way through the Gallows. In addition, Hawke was selected from a grid of 9 (18 if you count gender) characters, making the face feel like the most personalized experience.
Ultimately, Hawke's major failing is being the single commonality in every disappointing or frustrating DAII experience. That being said, Bioware has put a lot of time, effort, and money into redeeming themselves and this universe. I'm still a bit surprised at how far I've come from being ready to wash my hands of the franchise. I figure if Bioware is making the effort we've seen in Inquisition, a friendly/snarky/angry NPC with a customizable past shouldn't be too bad along the way.
If anything, this is Hawke's chance to be the anti-Anders* for those who weren't so stoked about the character the first time around.
*A small part of me wants Gaider's joke about DAII Anders being Ser Pounce-A-Lot to be revealed as truth.
I really don't buy into this logic. I actually enjoyed Hawke as a character and his story immensely. Unlike the Warden, Hawke actually had a personality and a voice, which added to the experience significantly. That wasn't my issue with DA2 at all. What was wrong with the game was purely on the gameplay side (lack of environments, step back in terms of combat, abilities, gear, companions, etc.). Had BioWare just maintained the same game design as DAO, but incorporated the story and Hawke the way he was, it would have been a masterpiece.
DAO was great and enjoyable, but the Warden was uninteresting due to lacking a voice and a personality. He was nothing more than an empty shell of an avatar I took control of for the sake of seeing other interesting characters (Loghain, Eamon, Alistair, Morrigan, Flemeth, etc.) take the stage. I found this incredibly frustrating as I always felt like an outsider and a sidekick to the large events. With Shepard and Hawke, I was actually at the forefront of these conflicts and my choices were heard through my character's voice. No longer was I ignored due to being a silent protagonist.
DAO's story may have been more "epic" and Awakening was certainly amazing. However, my Hawke was a thousand times more compelling and interesting than my Warden. That's just the reality of a character who actually has a voice versus one that doesn't.