Put quite simply, OneCare was nothing but a big massive patch to fix some of the things that were missing or working badly in Windows XP, which was the only operating system being sold at the time it originally released.
When those responsible for Windows os development realized this was why everyone liked OneCare, they finally fixed or added most of these features in Windows 7. Then Microsoft also created Microsoft Security Essentials, a free replacement for the antimalware portion of OneCare and released it ahead of Windows 7 late last year.
So rather than lament the loss of OneCare, smart people are either upgrading or replacing their PC with Windows 7, which gives them all of these features and many more built into the operating system itself, removing the need to continually pay for a separate program that does these things.
Those who choose to hold onto Windows XP have many third-party security and utility applications available to choose from, so Microsoft has simply decided to get out of that business and concentrate on what they should have been in the first place, continually improving the Windows operating system to remove the need for patch-on programs to 'fix' the os.
That's called 'innovation'.
Rob
