I don't think Tara has anything to do with this.
She does what QVC tells her to. When certain colors no longer sell well, they are discontinued.
New colors and new designs are added ro entice those who want something different or who want to start a new collection.
Taupe and Gray always sell out first, Those colors are hot right now and are guaranteed to sell. If there was a demand for eggplant floral lace, it would be available in everything too.