Maybe it was when you no longer needed WotC. You've collected an entire edition's worth of material (a hefty feat, to be sure!).
WotC reached a point to where they put out just about everything they could for 3.5. It reminded me of the end of 2nd edition. So when the ideas run out and profits sink, it's time to put out a new edition and get the higher dollar amounts one gets with core books. Enter 4th edition.
So here you are with everything from 3rd edition and the idea of collecting everything...again...is there in your thoughts. You may feel like you've been there and done that. You're not the target audience because you have it already; the target being those who don't.
I know that I feel that way at times. I had a pretty hefty 1e/2e collection, and I collected many of the same books in 3e as well (some better, some worse). Now here's 4e. I've already got two editions of Draconomicons and class/race sourcebooks. Now they're doing it again. It gets worse because of the ever-expanding core. So now this edition will have more than one Draconomicon, for example.
At some point, you have to ask why you need all this info again. The answer is that you don't. Of course, you don't need anything beyond the core three books. You don't need WotC to give you all the good dragon info (example) because you already have the Draconomicon from 3e. You don't need WotC to give you all the class options, because you have them already. And so on and so forth.
I could be off and this is just a guess. But it's a theory at least. My advice is to stick with 3e, if that's the game you like to play. You have plentiful resources which can provide years of fun to come. Maybe you're no longer WotC's target audience, but you may be the target audience for other companies. Take a look at what Paizo is doing.
Don't worry about being a target audience and buying things because it is WotC. Perhaps now is the time to focus on the fun you're going to have with all those 3.5 books.
