I made a cobblestone generator out of lava that i found under my house in Blackthorn (I ask a moderator before creating it) it took me some time and I burn at least 5 times but it is possible to make a cobble generator. As for the the lava and all that, well Lava is only good for creating cobblestone or obsidian and as a fuel in your furnace but its useless (unless you want to grief or simply kill players).

So it would be better if we leave the lava rule as it is. Although it would be a good idea if Mods could place the lava for good reasons