I am going to take the contrary, but a caveat first:
-- rock and roll as a sound has been essentially gone since the mid 1960s if you want to be technical. Rock and Roll described a beat and style. That is essentially gone and was replaced by ROCK, which was a testosterone fueled parody. At least according to an interview I read with Joni Mitchell, which I can't find on the interwebs, but damnit she said it and she was right.
-- that being said "rock and roll" has since become the brand for "music of young people," which has been attributed to tons of artists.
-- memories are convenient. People like to say "back in my day, music was awesome, we had (insert band names)," yet they forget that the big sellers were the Osmonds, Harry Nillson, Wham, Petula Clark, Tom Jones, NSync, etc. for the most part. Classic rock stations have cut the super pop stuff from your playlists and allow your mind to think, yeah, back in 1974 I listed to Steve Miller and Lou Reed and Bob Dylan all back to back on the radio. You likely didn't. AM Radio would have had Miller followed by the Osmonds followed by Jackson 5 followed by who the **** knows.
-- There are some amazing bands out there right now that have a great sound and if look hard enough, you can find and they have been around. The Black Keys, Kings of Leon, Vampire Weekend, Modest Mouse, the Strokes, Apache Relay are just some I like.
-- Now some of you may say, "well, **** you, get back on your bike, I never heard of those bands," or "**** you, I know those bands, and they suck," or "**** you, that's not rock and roll." However, again, how much of rock and roll was rock and roll? If you were "awesome" in the 1970s, you had Zeppelin, The Who, Floyd, Neil Young, etc....and guess what they were all very different. Neil Young didn't sound like Floyd, who did sound like Zeppelin, who didn't sound like you get the idea.... So, yeah, Apache Relay is as much rock and roll to me as most Neil Young in the mid 1970s.
-- Kids change how they appreciate music. Someone mentioned reading liner notes and the like. I did the same thing. That was "cool" in my day and yours. My father in the early 1960s? Rock was for going dancing and getting laid. My mom was late 1960s and music was lets' all turn on a beatles album, smoke something and feel the world change. They didn't understand why I had to blast Nirvana as loud as I could.
-- end of rant, now get of my lawn