Absolutely. There's a reason that task manager apps are popular downloads for every phone that offers multitasking. You won't see them on iPhone OS 4.0.
Android gives app developers enough rope to hang themselves, or at least waste the battery by constantly firing up the radio or GPS. I agree that you don't need a task manager to conserve memory, but there's no automatic solution for overactive apps except the automatic cleanup for long-running apps. Even the link you supplied admits it:
"Is it really necessary to be notified about every new tweet or status update? Reduce the refresh times on your social networking applications and reduce the number of items you’re notified about. Reduce the number of widgets you have on your home-screen, instead replace them with program shortcuts, you’ll still have quick access to your most used programs without the constant battery drain caused by continuous data pull."
