Nope ... everyone does not hate her.
I liked the character from the first time that I saw her ... okay, the pink and white armor was an eye-roll but her knocking out the drones was great. Here was this soldier who had just survived a geth attack after seeing her whole team die and she was eager to get back into the battle. While all of my Shepard's respected her courage and strength, my one Akuze Shepard felt a bond with her as a fellow lone survivor.
She continued to show herself even more capable at times than Shepard and Kaidan ... as those two focused on the dead turian, it was Ash that saw Cole first. She was also the one that spotted the salarian messing with the keeper. Ash was constantly on guard even when the others weren't. Maybe part of it was her need to be the best soldier.
She did not trust the other races but she could and did work with them. She learned to respect the salarians but she always knew that if they (aliens) ever had to choose between us or them ... they would save themselves. "I don’t mean we should mistreat them, Commander. I just think we should be prepared to go without them. As noble as the Council members seem now, if their backs are against the wall, they’ll abandon us." There were moments in the game that I was glad she didn't say, "Uh, Skipper ... Told you so."
Her spirituality was another part that I felt a connection to as well as her ability to respect that others may not feel the same. If Shepard asks her if she has a problem if he does not believe in God she answers, "Commander, I’m not some kind of zealot. I believe in God. What everyone else believes is their business." As someone who has friends from all different spiritual beliefs as well as agnostics & atheists ... I could relate to her.
You could see her softer side with the widower of one of her fallen sisters and if you look at her history she was well-respected by her DI and fellow soldiers. Her abilities should have pushed her farther but her grandfather's past sins had held her back. The Alliance brass used her to continue punishing her grandfather's surrender to the turians. Even Shepard notes that "your record is spotless, and your technical scores are exemplary. You should be serving with the fleet." She knew that but instead of cry or complain she just dug in harder ... worked harder ... hoping that one day she could clear her family name.
The fact that she is also close to her family was another bonus. Outside of her family's tarnished name, Ashley came from a pretty normal family that loved one another and looked out for each other. What a breath of fresh air in a day and age when characters have to be suffering mommy or daddy issues. The only area that I would have liked to really pick on her about was the poetry. Ash in ME1 was the kind of gal that I would have loved boxing with, drinking wine together in a bar and singing horrible karaoke with.
Horizon was tough. I could appreciate how she did not trust Shepard with Cerberus and respected her for calling Shepard out. Did I expect Ashley to leave the Alliance and join Cerberus? No. That would have gone against who I thought Ash was. But it also did not surprise me to learn that she had defended Shepard in her report (Anderson tells you that Ashley confirmed Shepard's story). I only wish that both the romanced and non-romanced Shepards had received letters.
ME3 is a little tougher because I only played it once and with my non-Ashley romanced Shepard. I did like how she protected Liara on Mars which was in line with her character. After Benezia died in ME1 it was Ashley that told Shepard that (s)he should check on Liara. Her questioning if Shepard was still in contact with Cerberus didn't bother me. It was a fair question and I always felt that Ashley was the type of person that was cautious to a fault. She wanted to believe but she was acting like my cousins from Missouri. Words were not going to cut it ... actions were.
Hearing that she was being made SpecTRe was not an issue either. If another human was to be promoted why not someone who had helped bring Saren down? Heck, she had just as much, if not more, achievements than Shepard did at the start of ME1. What had Shepard done? War Hero? Ashley was part of the team that had brought down Saren. Lone Survivor? Ashley had survived a geth attack and ... Saren. Ruthless? Once again ... was part of the team that saved the Citadel and potentially the Council. We also do not know what she did for the two years that Shepard was gone and all the time (outside of Horizon) after the Commander returned. In my book, if a human was to be promoted ... One of Shepard's crew were the most deserving. But then, I also don't think that Shepard could have been successful without her or the rrest of the team.
The fact that Ashley held a gun on Shepard was also not so horrible ... Wrex had done the same thing. She was doing what she thought was right. Protecting the Council. There were never any hard feelings and in my playthrough she sided with Shepard.
The drunk scene was okay as well ... they had watched Earth fall and the war was not going well. Heck, Dr. Chakwas got drunk, Tali got drunk, Shepard passed out on the Citadel ... If I were there, I'd have slept in a wine vat myself. So the fact that Ashley had gotten drunk in-between missions was not a problem. My problem was that the conversations with her were lacking. I was hoping to have a conversation that touched on their past or at the least mirrored past conversations. The cut content of Shepard and her dying would have been nice. Maybe one day I will play ME3 again and use the Shepard that romanced her.
Ashley was also the reason that I first created a male Shepard. If my female Shepard could not romance her ... well, I'd suffer through a male Shepard. I'm glad I did, though. Piers Shepard is now my second favorite Shepard and he allowed me to see different sides of both Ashley and Miranda.
You may hate or dislike Ashley for personal or story related reasons ... I don't see why that should bother me or anyone else. This is an RPG and how we as the players or our characters feel is up to us. It's our own sandbox. Even though I love the character, I also have a Shepard that hates Ash. He actually can't stand most people but he hides it very well. For me, it's all about the story and the Shepard you are creating.