Well if physics theorizes that energy can never be destroyed but only change into another form, I don't want that energy bugging me. I am bugged enough already by being annoyed by everything.

its just polite and doesn't need to be picked at or thought to death

Because they don't want you to come back and annoy them again.

Yeah I guess it doesn't make much sense to give a direction to a dead person. That term RIP has always sounded like a religious term, so I notice many people use other terms, such as "rest in paradise" and such.

Maybe if one wants to wish the memory of the dead person well, something more along the line of "rest gently in the hearts and minds of those who love you" would be more thoughtful.

It's probably just wisest to direct any comments to the loved ones instead of the dead person. "I'm reminded of her smile every time I (whatever)" might give some solace to those who are grieving.

I, personally, like this saying because I personally think life usually sucks ass .

Difficult to have any emotions after death, really.