Fire can produce charred objects

Its kinda boring that trees disappear when burning it up , or that fire doesnt spread across grass blocks. I think when a flammable object is on fire it should have a 30% of turning into the charred version of its self but %70 to burn away. Also I suggest fire can spread/move across grass blocks and turn them into course dirt so they will never have grass on them again .  Also Forest Fires could have a chance to appear and leave behind a charred forest! And last , is that mossy stone , cobble etc. , when burned only leaves behind the block without moss . By CreeperLeviathan.