I make all my objects with physics shape. That's how it need to be.
I find on scenes enough tree's as example that are phantom. Meh.
Now it's a problem if there's no physics. I hope people stop putting objects on marketplace without it.
But the other side is tha when you have a physics to object. you never can disable it (phantom in SL) and am pretty sure there are cases that you want to have the physics shape disable / removed or it's not needed.
So some option in object properties where you can say "No Physics Shape" would be good.