Is it necessary to use the eastern asanas or positions to meditate (The seated on the floor one,) and is this preferable to music? Do these poses have some benefit to them?

The reason I ask is because meditation, from my understanding is meant to be a constant practice from moment to moment. So why spend 20 mins a day in a seated position when u can meditate through observing ur thoughts anyway?

Aside from seated meditation, how do we meditate during daily chores and activities? Or is the point of seated meditation to unlock our conciousness for the rest of the day?