It`s not neccesarily that "so much changed". It`s just one man, who made a claim. Imagine that Muhammad and other prophets were just one man too, but they changed all of society. Now if just one man makes a claim that seems to go with these teachings, and it gets popular, that again changes things. Unfortunately with the hadith, in a negative way.
Looking from my experience with music, and getting known, idolaters seem likely to try and change peoples perception of you, into a satan, as soon as they gain knowledge of you. When other people say "he is a good artist", they would add satanic statements "and probably a big <insert devil-properties here>". They read into the artist all the know from idols, he has money, power, all the women he can want, etc. Soon they are seeing satan. In an online archive where I was popular, a song I did not make, was added "give your soul to satan". It further strenghtened their idea of me, being a satan. When I went online on IRC, and went to the place where these people were, they expected a satan, not a kind man. So when I was a kind man, I became unpopular, and this image they created of me, seemed to live on, on it`s own.
I am ofcourse saying this because, Mohammed has been treated in a similar way in hadith. They turned him into a satan. Prayers were exaggarated, and repetitions included, until it resembled a obsessive-compulsive ritual, rather than honest dialogue with God. Mohammed was turned into a man who made nonsensical remarks, and Islam was turned into a religion were simple things could be done, and one gained paradise, regardless of morality. Even papers on how to piss and shit, were included, and called religion.
Now, I started with music when I was around 13. Or even earlier really, but I made my first track then. (on amiga soundtracker).
So I discovered this about myself around about 1999, when I started using IRC, and got internet at home. I was 23. So in ten years, one could see a certain development. Now I made myself quite clear on the internet that I wasn`t this person, and also I became interested in the study of religion, and made a www-page detailing the concentrate of my belief. So that may have succeeded in killing that original satanic development, of how I was percieved in certain online environments. Because today they seem aware that I am a religious person. Some of them have therefore started to call me crazy, and know I am against homophilia also, so they gay try to slander me, and often try to portray me as evil. I feel no sorrow for this though, I am confident in my faith. I have a LOT of joy, because of my faith

BUT if Mohammed lived today, and could simply put up a webpage, I think that hadith-culture would have been killed, and people would see him for what he is.
Mohammed is a man of high morality. Of excellent character and of high intelligence. I think he knew mysteries that most do not, and posessed an unusually high rank in the angelic realm. There is no scripture like this, and has never been. Instead in the Quran, Mohammed is presented as someone who tries to follow God. And even that is shrouded in mystery. I think the mind of Mohammed, is a mystery to most. Unpercievable.
Unfortunately because he is a mystery, people can attribute sayings to him, and turn him into a satanic image they know. I mean after all, satan seems common in the world. Angelic nature seems unknown. Indeed, they have no idea.
Does a man, who KNOWS God, and therefore FEARS God, behave and say the stupid things in hadith. Again, ofcourse not.
There is a certain logic, in The Quran. The idolaters, have no ears or eyes. Sometimes even Mohammed is told by God "have you no sense".
Intelligence seems neccesary. And satan follows his desire.
A man of Mohammeds rank, cannot be the shaitan in hadith. He must be intelligent, and the Quran says, that he is to "follow such a Quran".
Hadithists often quote the verse of Mohammed being a good example. But then they should follow The Quran, like Mohammed did.
Quran doesn`t state, and then you shall follow Quran, and your own sunna. That would be nonsense. No, Mohammed was to follow The Quran.
And ofcourse, he followed The Quran, and embraced the morality of it. And thus shaitan-mohammed in hadith, can be ruled out.
No mindlessness attributed to Mohammed in hadith, can be true. And to gain the position as messenger of God, he must have had a very high rank to begin with also. Probably very intelligent, thinking, and monotheistic.
But the idolater doesn`t see this.
Indeed the atheist Kader Adbolah says on translating The Quran, and writing about Mohammed from hadith,
"I found myself". (0:45)Now he can mean a lot with this, but he also repeats the same lie, that one cannot understand the Quran if one does not understand hadith-Mohammed. And he is an atheist. Ofcourse an atheist cannot understand the Quran. But the hadiths, he is presented as a shaitan like himself. THEN he "understands".

That is probably why the quran is so overlooked by sunnis also. The same mechanism are there. They have this satanic mohammed in hadith, which forms their view on the Quran. Now we had a couple of hadithists in here. And satan follows his desire (quran). They seem to descend into sexual thinking, almost the minute they got here. They understand the satanic mohammed in hadith, and not the Quran.
Mohammed and similar gnostics, would not be popular among them. Just like I was rejected among those who worshipped an image of me, instead of liking the religious values I stood for, have done the same thing with Mohammed.
And I am a gnostic too, and have done a lot of thinking on religion. And that gets me banned in the local sunni forum..
Indeed, the jews "banned" Jesus, and wanted him crucified. And the christians would probably ban Jesus, as he rejects the trinity. And Mohammed would probably be banned, because he rejects "sunna". (He was ordained by God, to follow The Quran).
.. Peace!