There is a lot of evidence of him becoming a hate figure. When people are judging weather a director is popular or not they normally just look at how much money their films are making. But that hardly reflects how people really feel about them. The Matrix Reloaded made a lot of money, but I would have trouble finding anyone who actually thought it was any good. Just look at any of the Spielberg related discussions on the IMDB boards. People think of him as a symbol of Hollywood superficiality (though at a time when Hollywood has sunk to new lows he is really one of the few people holding it together).
Let me introduce another angle of anti-Spielbergism. It's generaly among film buffs that he is a hate figure, which is why lots of people are still spending money to see his films, but the fact that it is fasionable to critisise him effects people, probably without them even thinking about it.
There was an ocasion recently (well, about a year ago) when I was talking about films at school (I'm out of school now thank God). This one guy was basicaly taking the piss out of me for liking Spielberg. Now I seriously doubt if he could actually name 5 films that Spielberg has made (I'l also add that he was the sort of person who thinks that Lagaan is the greatest film ever made in India, and thinks that the grades you get in school reflect your intellegence). Steven S has made films that appeal to children (and some of you need to realise that that doesn't mean they are just for children), so it is fasionable to say "oh Spielberg isn't cool, his films are just for little kids. Tarantino - he's cool".
Another interesting thing is that he has had such an influence on family movies of the last 20 or so years that many people sometimes need reminding that he DIDN'T make Free Willy.
It is always going to be fasionable to criticise something that has mass appeal (the "it makes a lot of money so it must be crap" phenomenon). People have similar attitudes to Chaplin. He's had such mass popularity that he has trouble getting recognised as a serious artist and it's fasionable (I've got to think of another word to use) to favour Keaton of Tati. I think that the critics are gradually starting to treat Tarantino in the same way.
Yet another angle: people critisise Spielberg because...thay can. Let me explain: I'm not a great fan of Bergman, but I do reognise that he is a master film maker. I really didn't like Wild Strawberrys, and if I'd seen it anonymously, not knowing who directed it, I might have taken the view that it was a bad film. However, knowing that it was a highly aclaimed film, and not being one to take the view that all the people who rate it are idiots, I assumed that there was probably something that I had missed, and did managed to admire Bergman's technique. Now when you have the same sort of experience with a Spielberg film, you don't feel that you HAVE to give it a chance, because he is known as a mainstreem director and not as an artist. So if yo don't quite get ti, or it just doesn't hit you on a gut level, then you can choose to say "it is crap". I am certain that if he had made all of his films in French, people would take him a lot more seriously.
Anyway, getting back to my origonal point, if you take a look at the IMDB discussions on Spielberg (mostly on the best/worst voards) you'l find that he is beggining to become a hait figure.