To use DnD alignments, I've always seen the First Order as being Lawful Evil, and a great counterpoint to the rather Chaotic alignment of the One Sith. The Sith ruled through power and fear, and while the level of oppression varied from place to place (it was reasonably well established via internal lore that the core worlds were doing pretty damn well under the Sith, a decade of constant war aside) there's still that environment of being run by folks who see murder as a fun pastime.
Uh, obviously that'd be awful in real life but that's why we're writing here, you know? The One Sith were an Imperialist (not 'Imperial') faction built on conquest. Keeping your core territory peaceful so you can maintain an expanding front line is vital to the war effort, but at the end of the day you're still 'evil' even if little Timmy enjoys a better standard of living than his parents did (because he reaps the benefits of subjugation and looting).
The First Order is different though. Since I've joined the faction it's always had a clear vision of how things are structured internally and how life works for its average citizen. The laws can be strict but they're enforced rather uniformly. Sure there's limited options for political dissent but neither does the government act like a kleptocracy. It's expansionist and Imperialist, but always with a mindset towards a well established goal.
In other words the First Order is an intelligent, calculating, almost benign sort of evil. The kind it's probably easy to imagine coming to power in a formerly backwater region of space. It promises stability, growth, security, and prosperity, and the only cost is a little bit of your personal freedom. In other words it's one of those really good villains that you can't help but love to watch. It's Tarkin compared to Darth Vader, or Thrawn compared to, uh, well the canon First Order (who have no clear goals or methods beyond being boring bad guys who blow up planets). The First Order is smooth, suave, when it says 'you'd be better off under my protection' you can't help but agree.
But you did just still get annexed unwillingly, and then you remember that's kind of the FO's modus operandi, and at the end of the day they're still the bad guys.
That's how I view it, anyway. The FO is a bad guy with a plan and a purpose, and that's a hell of a lot of fun to write for, and write against.
As for the OOC hostility (perceived or real) I'm not sure where that's coming from. People projecting their values on their characters, perhaps?