Barre chords are indeed very difficult at first, but they get easier with time, due to building muscle strength. But more importantly, these guys who make this look so simple, are usually not barring all the strings. You don't have to. You just have to barre the strings you're going to be picking.

For example, in an EAB shuffle, to barre the A, go up to the 5th fret, and bar with the index finger across the 5th fret, and make an "E" formation with the other 3 fingers. To play the shuffle, you're going to move your pinky around, (ala SRV, "The House Is A Rockin"), but you don't have to bar all the strings to make this sound right. Just the bottom 3.

And so on. Get it? Ease up on the index and just barre what you need to. PLC