I believe the core reasons monsters haven't been added is that, the wikidot is (at least in my own eyes, others here might have a different input) designed with a player focus, rather than a DM one, so each resource here would be something a player might need to reference in game / use in character creation.
A majority of the time, monsters are going to be used by the DM, rather than the player (with the most probable exception of Druids and some spells)
Admittedly, it is a bit annoying to not have the animals you wish to wildshape/summon be available on the wikidot, but yeah…
Thats sorta the idea behind my own thinking. Though once again, others on the team might have different reasons
