Why do so many rock fans claim that Country Music sucks when they know all the words to the Country song?

Actually it's a small percentage of people who like rock that dislike country music. But they're also among the most vocal in expressing that hatred. They're also among those who like to pigeonhole others who listen to country, and will mock them for liking it.

As to the statement about country not having changed in the past fifty plus years, this is false. Ask any fan of traditional sounding country, if the country sounds anything like it did in the 1950's and it will be almost total in agreement that it doesn't sound anywhere near the same.

I agree with Wendigo.

Take a look at the following:

"I Walk the Line" (1956)

"Crazy" (1962)

"I Will Always Love You" (1974)

"Forever and Ever, Amen" (1987)

"Breathe" (1999)

"Save a Horse (Ride a Cowboy)" (2004)

"Time is Love" (2012)

These are just one song from each decade frrom the 1950's onward and you can't say that they are remarkably similar.

Because the words haven't changed to the music since Roy Orbison in the 50's