Trixie Belden and the Mystery of the Memorial Day Fire; Trixie Belden and the Pet Show Mystery

Yesterday I reread two Trixie Belden's by Kathryn Kenny that I haven't read in about 14 years, so while they were vaguely familiar, I had forgotten the particulars, which is always nice. The Memorial Day Fire has Trixie and the rest of the Bob-Whites investigating a possible arson at their friend's father's store, in which the father is the primary suspect. The Pet Show Mystery has Trixie and friends holding a pet show to raise money to feed the birds that are slowly starving because of the harsh, cold winter, and entangled with a gem smuggler posing as a philanthropist for human hunger causes. I miss Trixie. Why did they stop writing them? She was so much more entertaining then Nancy Drew.