A couple years ago we were selling all of the plug-ins individually and the reverb alone was priced at $699. As the catalog grew we realized we were spending a lot of time maintaining all the seperate products and if we just released one bundle we could afford to sell all 10 for $999. When we upgraded to Anthology II the number of plug-ins jumped to 15 and the cost of maintaining each of those seperate products would be high, so that is why we've been reluctant to do that hoping that $999 would still be a very good deal for all you get.
Though I'm sure it wasn't the answer you were hoping for I hope that answers your question.
Is it very important to you to purchase your plug-ins a la carte?