QuadFX was a failure - they dropped it like a hot piece of iron,so left the users high and dry after one generation. They made socket 754 gimped so it would force people to socket 939 which made them more money.
The issue is AMD has publically said they want to not be a "budget brand" and have told investors they want to target higher end markets,instead of "lower end" markets. Its the same type of strategy - just ignore the lower end and mainstream markets,and hope PC builders just get expensive products. In fact Intel and Nvidia did the same - just make the lower end stuff pretty rubbish,so everyone trades up to higher tiers. Now AMD is jumping in,you will see where things are heading.
Just look at their GPU prices - Nvidia is basically better value!