The company was quick to point out that with push notifications, multitasking becomes less important and users would still be notified of important events as they occur. Sound familiar? Well, that was the precise reasoning that
Microsoft's justification is that given the time frame--they were working with a radical redesign of the OS--multitasking did not fit into the timeline. However, that doesn't mean that the company isn't considering that feature for future updates or revisions.
Push was primarily chosen as an alternative to multitasking to enhance the user experience--a recurring theme that we've been hearing since the announcement of Windows Phone 7 Series at Mobile World Congress. Microsoft believes that push notification will give users longevity in battery life between recharges, will allow the device to better manage memory without app slowdown or lockups, and will give users important updates.