When I first started playing Brawl competitively, most of the people I faced were Melee-esk in their aggression. It was fairly fun and entertaining, and although IMO nowhere near as good as Melee, it was a new game I felt I could be really good at, as I was beating some fairly high level Bay Area opponents.
However, once everyone starting running away from their opponents and attacking as their "offense" or waited for their opponent to move, I didn't make the adjustment, and I went from being able to hang with the best to being creamed by the worst of competitive players. And when I made the adjustment and won a few matches, it made me not enjoy the game, and it was even worse than lose.
While I don't agree with their disdain for Sakurai (I blame Game Arts, Iwata, and the Wii more so), it's not hard to see where they're coming from considering their history with the game, especially since I went through the same thing.
I had everything I wanted: A new Smash game on a new console, a sequel to my favorite game ever, my most wanted stage (Delfino Plaza) being tournament legal and a great counter-pick for me, my favorite smash stage ever (Rainbow Cruise) being tournament legal and a great counter-pick for me, my favorite video game character ever being my favorite and best character (Toon Link) who was actually tournament viable and fairly underrated, and a huge (local) competitive community, but the game just wasn't fun competitively (once people realized the best [and cheapest] way to play it competitively to win).
Like many of these people you're demonizing, I spend hundreds of hours hyping the game, playing the game, mastering the game (I learned over 6 dozen brand new advanced techniques; that's not counting the techniques from Smash 64 and Melee) only to have it be a terrible competitive game. It was boring, lackluster, tedious, and nowhere near deep at the competitive level, as a player, a spectator, and a "fan."
Once you realize that most of those people went through that and especially once you experience that, you'll sympathize with them. It feels like something you worked towards was stolen from you, but actually, you realize it was a lie. The game you were promised from the demos was a lie.
All that cool stuff in the demo was gone. The combos, the incredible balance, characters like Bowser, Mario, and Pit having awesome moves, the sweet finishes and spikes, the game being fun at any level of play, and the new techniques were all removed from a demo 3 months ago. And the funny thing is, they made the game worse for casuals, too. Random tripping was much more rare, and they might have actually added Mewtwo in that time. But no, they had to make the game less enjoyable and competitively centered around stalling and camping to where most of the potential competitive community turned away from the game (competitively and casually).
That right there is the biggest reason I think Brawl deserves all the hate it gets, and why we all hate it. We all didn't just forget all that demo stuff; we remember it. After that happened to me, I considered selling my copy of Brawl and never buying a new Smash Bros. game again. I felt cheated out of my time. But then when I discovered good mods at a Melee tournament after I dropped Brawl competitively (Brawl Plus and Balanced Brawl), and I changed my mind. That's where I recaptured much of my hype for new smash bros games, and probably why I still care about Smash Bros sequels.
Oh and part of that demo removal stuff and the general bad decisions was probably partially Sakurai's fault. Still, most of the Project M, Smash 64, and Melee crowd still give credit to Sakurai for making the series, and for making Smash 64 and Melee into great (competitive games), but their dislike of his moves with Brawl are understandable, although sometimes exaggerated.
And quite frankly, sometimes hating on that game mutually is a way of bonding (your experiences) because of these experiences I just mentioned me and thousands of other competitive smashers went through.
Sorry for the long post guys, but it needed to be said. And because of all this crap, Brawl really freaking annoys me. And we didn't even get a playable Ridley!