It's a fascinating thread, which has wavered from "Do writer's hate Hank Pym" to basically portraying everyone's thoughts on redemption. It's not unlike people arguing whether prison should be for reform or for punishment. It's also fascinating that many people in general accept villains turning good, and ride with that, but can't get past a Hank screwing up and trying to be a hero again. That's really the thing of it at the end. This conversation is far more about the personal belief systems of the commenters, and those belief systems rarely change. I, personally, think that there's some hypocrisy. Magneto can commit extreme acts of terrorism and decide to join the X-Men the next day and no one really bats an eye. I think, objectively, if you believe slapping your wife in the middle of a mental breakdown is worse than putting a bunch of innocent humans in danger of being murdered, to the point where you can't hate Magneto with the same vigor when he's palling around with his new best friends X-Men, that has very little to do with what's on the pages of a comic book. People really liked heroic Doom. People really like heroic Namor. Namor keeps drowning people, and no one really has a problem with him showing up to work the next day like, "I'm a hero now. Yesterday? Yesterday I just didn't take my meds." Namor drowns people, or recently forces big lifestyle changes on them, he sits on his thrown after and more often than not ignores the consequences of his actions. Hank did something wrong, acknowledged it, and made the effort to set things right an number of times. Thus, we come down to my own personal belief, which is that the effort matters, perhaps even more than the act itself.
Btw, this is not a call to arms against Magneto or Namor, I greatly enjoy both of these characters myself. Because it's fiction.
As for Ultron, Hank will be trying to redeem himself for that forever, but that's pretty much the average relationship between a hero and his or her primary villain, as was mentioned above.
Do writers hate Hank Pym? Honestly, I think it's mostly indifference. People don't know how long they're going to keep getting these Marvel gigs, they don't know how long they're books are going to be, so they want to use their favorites while they can if at all possible. All the people that like Pym have already written him, and the one thing Pymtron specifically has going for him is that it's easier to incorporate a villain into a story than a hero. I think there's an argument to be made that Remender had it out for Pym. There's an argument to be made that Gerry Duggan doesn't like Pym (Oh, I know he said he does, but is there anything more disrespectful than having a characters soul get eaten? Kill your darlings is one thing but COME ON! That's said, could have been the play to remove him from Pymtron and Pymtron's actions). I think editors just don't know what to do with Hank, so they let writers do whatever.