I feel like it's a bit of a waste that these spells have no effect on Plant creatures. They could be analogous to Enlarge and Reduce Person for them. Now, I know Plant creatures are not very popular or prominent in almost any campaign, but I like the playable Ghoran, and I'm sure someone else somewhere out there does too.
Would these spells operating like the equivalent humanoid versions for plant types break anything, or is this a harmless change to the spell?