Pilots are usually shown to execs, who give it the green light for full production.
Knowing that, and with execs probably knowing Katey Sagal (Cate) was known as Peggy Bundy in the most dysfunctional show ever, "Married with Children", keeping her on the backburner wasn't unwise a move to make.
Having said that, future episodes readily prove WHY she was chosen to play Cate. Katey's performance does NOT make people equate her with Peggy B, with Cate being an actual caring mother, while still allowing her to exhibit a sardonic wit that she, as an actress, is known for doing well. Later episodes present more of Katey, which only solidifies how right the producers were in casting her. A brave decision, which paid off immensely. She truly is a wonderful actress.
The casting in this show was simply perfect. The actors are all of high quality and professional. I know I've been Katey-centric, mostly because I'm tying general show comments in with the pilot; an episode which sets up the family dynamics with aplomb. The confidence is assured. The writing in this show was simply perfect. The usual tropes exist, but the end-runs and creative workarounds show what creativity is meant to be, and proving television is not a dead industry. Then add in the occasional moment where the parent sees the teenager as a little girl and it knows how to emote without wallowing in it either.
A first class family show, "8 Simple Rules" was. For those and many more reasons.
A shame ABC killed it by moving the show into a Friday time slot (which only assures a ratings drop because nobody's home to watch it!); while the dynamic changed because of John Ritter's untimely death, the incorporation of it into the show was a stroke of brilliance, and the characters created to fill the void work -- and were wonderfully cast too.