I don't think I've ever experienced this first hand, but it's kind of crazy to me that music used to be capable of causing riots when it didn't conform to people's expectations.  Probably the most famous case is the premiere of Stravinsky's The Rite of Spring, which people were so scandalized and outraged by that all hell apparently broke loose in the concert hall.  That would have been something to see.  I've heard the Rite of Spring and it's a perfectly nice piece of music, but it's difficult to imagine anyone getting up in arms about it.  But they did.

To a lesser extent people were pretty angry when Bob Dylan went electric.  I don't know if they rioted as much but I know it was a source of great unhappiness to the folkie purists and it wouldn't surprise me at all if a few angry shoves were exchanged back and forth.  Nowadays when I listen to Bringing it All Back Home, the record on which Dylan first plugged in, at least for like one side of the record, I barely even register that there's a difference between the electric and acoustic songs.  It's not exactly like he was busting out Metallica style heavy distortion and riffage.  Nonetheless people were incensed.  

It's hard to think that such a thing could happen these days.  Maybe if there was a singer you really liked who drastically changed their style to something you didn't like you would be mildly disgruntled and perhaps not listen to the new stuff, and undoubtedly some people would complain loudly on the internet, but it overall wouldn't be that big of a blip.  I think it's a combination of people being overall more exposed to different styles of music so a change wouldn't be as jarring and unfamiliar, and also music just doesn't seem to have the widespread cultural impact it once did.  There's just too much of it and people listen to too many different things for any one musician to upset the entire world simply by sounding different than they used to.