You don't need to do everything on that list, but you'll need to do the majority of things on that list if you want a properly running SHO that'll give you a minimum of headaches. Not everyone here lays out that sort of investment at once; most do it gradually over time, starting with the imperitive items first and going from there.
And to be honest, I'd much rather see someone who is willing to make some sort of an investment in their SHO to see that it's running well for the long run, than someone who realizes that it's not as cheap as a regular Taurus, and ends up junking it when something expensive breaks. Owners who know and understand what it is to own a SHO are the key to keeping these cars around. Not people who get scared when they can't get a part at "the Zone".