Welcome to mapster.
Im not sure what "simple things" are missing but being that your new its mostly likely your just unfamaliar with how things are actually done. Doodads for the most part are just inanimate "models" that sit on the terrain and can effect pathing. Any model can be turned into a doodad including ones like those used in units. There is an assets page (top tabs) that can various custom additions for models and other such things.
There are bridges in the editor but these will also usually link with like a terrain object since i needs to interact with the ground itself. As far as things like caves the truth is is that is really absolutely is up to how creating the artist is and how longs they spend. Count on anything that looks really really nice or is not what you usually see is in fact something someone has already spent a great deal of time on and thats exactly why it looks so good. Keep in mind that in most of the high end melee maps there is roughly 1000 doodads per player alone.
Mapping in general can take a lot of commitment, a lot of time, and requires you to be a self starter. Best of luck in your own designs.
When I want your opinion...I'll give it to you!
SuperiorHHH Regular ShmoeIt may be because i am completely new to the editor and just don't have any idea at all where to find any doodads (probably the case)
But after hours of going through doodads I'm beginning to wonder why simple things are not in them. And that led me to this question: Are there any downloads of player created doodads in CAD or other 3D models? I'm curious to see if there are things like more bridges, caves and things that you can't find in the editor or have to work hours just to create a certain look of something.
Hopefully I'm making sense.
Any help is greatly appreciated. Thank you!