Ok, thats fair enough.
I did have this other idea for 'hardcore ecology' which makes the world a little more dynamic and destructive based on player activity.
Essentially this uses the same spreading mechanic as grass to allow other plants to take over.
Mycelium can spread over grass/podzol/farmland at the same speed it can over dirt.
This would uproot plants/crops/saplings ect.
Mycelium can sometimes grow small red/brown mushrooms as long as there isn't too many in the immediate area. (say max 5 per 5x5 area centered on the shroom)
Leaf/vine blocks vertically above mycelium slowly decay.
The overall effect of this would appear like the mycelium taking over and growing into a fungi forest.
TiCon slime-grass blocks would also have a similar effect;
Grows over dirt/grass/podzol etc at twice normal rate.
Grows over mycelium at 4x normal rate.
Dirt blocks touching slimegrass/slimy mud will convert to slimy mud at normal rate
Slimy mud grows into slime-grass in direct sunlight
Converts leaves/vines/logs ect into slime version. Mushroom blocks convert to slimy wood.
The liquid slime (found in slime islands) will rapidly convert grass/dirt to slimy mud on contact.