Therein lies the disconnect for me.  Not that I don't see the value you derive from it, that much is plain and good.  

  For me, the cost of the books don't justify the bits and pieces.  I won't spend $50+ for a tiny sliver of useful content.  The bits and pieces I find useful are the character options.  That's about it.  The adventures or pieces thereof are of no use to me, as I create my own.
For those with far more limited time but still want to create their own adventures/worlds, then what you suggest is quite an excellent way to go about it and by no means do I disparage those who do it and enjoy it.