Admittedly Even if I had an all in one, I would still have separate spyware software but I'm a security freak .
But an all in one package is good for your average user, many dont know how to use spyware or virus products. An all in one system would be easier for them, and if all you do is download music browse the web and check mail it`ll work just fine.
It would Also cut down memory usage just have one program, Im sure its the way forward.
I understand your point and I would also have separate spyware software if i were to use a all in one....you never know an all in one package may not be updated properly or not have sufficent protection Better safe than sorry.