The notion of dead people being able to see and hear begs the question of what then is the point, or the difference, in being alive. Seeing is a highly procured information flow through a complex visual system, likewise, hearing is another modal phenomenological information flow through a system. Evolution has honed these information systems over billions of years, seems a bit of a waste of time if it all that complex information flow is just there somehow by magic.
Being alive you have a body, you can reproduce, explore, and experience the universe in a different way.
You can also relate to others and learn.
Normally it's the religious that look for a purpose in life.

There doesn't have to be a purpose we understand totally, perhaps the difference is being alive we have to " work it out for ourselves".
Perhaps we don't learn and experience in the same way if we are formless concienceness.
It isn't any more " mad" than scientists who suggest the universe is like a huge simulation.
Maybe it is

Perhaps whatever is, wants our experiences within what we think of as the natural world.
Who knows what some alien super being could want?
It may want something from us we consider more mundane, like our daily struggles etc.
Like a reality programme. Perhaps it's that our bodies limit our experiences making them more interesting to whatever wants them.
We will have to explore and wait and see.
Perhaps what ever started off the universe wants to experience the whole of its creation, from the first few cells of life.