I don't spend much time on /m/ but over the years when I stick my head in I notice that there is a lot of hate for G-Wing.
If you spent more time you'd realize there's hate for just about every series, or the ones people actually saw. Finally after spending more time it becomes apparent that there's little genuine hate.
It is against the law here on /m/ to like any mecha anime. Besides, why would you pay any attention to what some random shitposter dislikes.
As for Gundam Wing: it is a mixture of good and bad, like any Gundam.
I'm watching Wing right now. I've seen every other Gundam from Turn A and before and figured I might as well watch Wing just to say I did. I'm only on episode 16 right now, so I haven't solidified my opinion, but from what I've seen so far it's just nonsensical. It's one of those shows where something has to happen every scene regardless of if it makes sense or was set up. Like I just got done with an episode where Relena manages to sneak into a ball because coincidentally an old guy covers for her, which coincidentally is someone who exposition about the Peacecrafts for 30 seconds, then coincidentally that Une bitch walks in, then Relena pulls an established gun literally out of her ass, misses at close range, then runs off only to coincidentally get saved by the girl that loves Zechs. It feels like I'm watching a fever dream, and honestly, I kinda like it in an ironic sense. If I don't take it too seriously, then it can actually be kinda fun. I've heard it kinda stalls towards the middle though, though, so I might end just hating it by the end, But so far, it's been enjoyable shit.
Continued - I think the people that straight up hate Wing are more so just tired of people saying it's amazing despite not having watched it in 10 years. Or whenever you bring up Gundam, they respond with "oh yeah Heero was cool. I loved Gundam Wing back on Toonami." I think a lot of people are just tired of a pretty mediocre show getting so much love and main stream appeal simply because of nostalgia.
It was the first gundam for a lot of people, but similarly a lot of people didn't see it as their first and are more objective about grading it.
The real truth of the series' value is somewhere between the nostalgia and the anti-popularity hipsters.
It is a fun series, but come midway through the first season, it has some heavy flaws in the plot. The animation really suffered immensely from the horrendous re-use of stock footage (I'm not sure how many times the freaking Heavyarms gundam has the same freaking shot over and over, or how many times that same Leo exploded).
Really, it had a of things set up for it to be good, but the story begins to shit the bed. Strong characters put into completely useless situations, and then shoehorned into the final arc with Libra falling onto Earth that makes you completely unsure of what the hell anybody was doing for what reasoning. Then Endless Waltz makes that same mistake again.
At least it was popular though. I don't get why Wing gets so much hate, and Seed gets tentatively less on /m/. They're really the same show in different decades when you get down to the nuts and bolts.