What would be nice is if there were some mechanic to have FoL civs able to improve their forests more. Perhaps FoL priests could plant a baby forst on a tile with an improvement (cottage, farm, etc.) that has no effect for several turns. Eventually it will mature into a forest and then an ancient forest.
I know, people are going to say that this tramples on the special effect of the elves. I don't think that it really does though. Elves can build improvements in existing forests and can do so from the beginning of the game. This new mechanic would just allow FoL players to develop forests on existing improvements. It would be a mid to late game boon to an already developed city rather than an early game boost that the elves have. This mechanic would also be useful for elves so that they do not have to raze their improvements to cast Bloom and then rebuild improvements in the forest.