I personally think there is an added value in more complicated node maps (as long as they're done sensibly, and not just about adding more nodes), because I think the AI tends to fare better thanks to more useful attack vectors being created.
The AI doesn't use the nodes to determine attack vectors. I think there might be a misunderstanding how the AI/nodes works.
At the beginning of a mission all the aliens are set for Patrol mode and spawned in the nodes. While on Patrol mode they will use the nodes to move around and look for XCom units.
When an alien unit spots an XCom one, then the AI will switch the mode from Patrol to Attack/Ambush/Retreat, depending on its aggression, etc., and
it will stop using the nodes for movement. Instead it will move the alien to where there is cover, etc., and completely ignore the nodes.
If the alien stops seeing XCom units for X turns (X = intelligence stat) then it will revert back to Patrol mode and use again the nodes.
Now, you can place nodes in locations where you think it may be more advantageous for the aliens to reaction fire your soldiers (to the side of the door instead of in front of it, etc.) but this can be a rather useless effort for a number of reasons:
* You can't control the direction that the alien will be facing. If you place a node like Dioxine said, then it will be likely that the alien will be facing the wall next to the door rather than the door. Then XCom unit enters, turns around and shoots alien on its side.
* You can't control how much an alien moves during its turn, thus the alien might not have TUs to reach a certain node during its turn or have enough TUs for go through several nodes during its turn.
So, when you are designing nodes you need to take into account all of these factors. And it is really better and easier to keep the patrol routes simple. And the best example comes from TFTD - if you compare its maps with UFO's you'll see that its nodes are much more simplified.