Why do D&D books suck?

I've heard all Dragonlance books not written by Weis/Hickman suck, and all Forgotten Realm books not by Salvatore suck.  What in particular makes these books suck?

I couldnt get past page forty of the very first DragonLance book beause it read like fucking notations of a D&D session. They even said so (anotated anniversary edition I borrowed), ever five friggin paragraphs.