Rick dead doesn't make the show more interesting in my opinion.
It would be a hell of a lot more interesting because it's the hard choice and forces the writers to really keep a drama series fresh.
In your opinion. Just like mine is an opinion. Killing off main characters just for that reason isn't good enough to me. Plenty of "fresh" going on for me. Game of Thrones may be more anyone can die, doesn't make WD obvious.
EDIT- I didn't state that as meant. Killing off a main character does keep things fresh, but it doesn't mean you do it just because that is the case.
P.S. I think WD has killed off so many main characters they run the risk of not having enough time do develop the "newer" characters and that would not make for interesting TV. I can watch a bad zombie movie for that.