You know, I GMed 4e for 10 years straight, game after game, and I have never read through the list of powers of any class in order, not once. Skimmed, perhaps. Definitely read specific slots worth of powers, all of a PP or ED, etc. Classes I have not played or GMed, I have some notion of what their powers are like, sure, but I have probably never read 80% of them.
So, if you play a class 1-30, yes, you probably will read all that, but otherwise there's little point in doing so, unless you find it interesting.