That drawing which depicts the deck ending before reaching the window on the rim is kind of odd...
Has anyone suggested such a set-up before?
As I pointed out before, we never saw anything in the outer rim of the saucer... at all. The cabins are based on the set design (using a different radial component for the walls). But because every compartment needs to be self-sufficient a commons area seemed like the best use of the very small area of each of the four outer rim compartments near the windows.
To answer your question, Andrew Probert suggested a similar split level rec area design for the TMP Enterprise at one point. But I hope that you aren't saying that you've never seen an indoor balcony setup before.
The rim windows didn't work with anything seen on-screen and unlike other parts of the ship, didn't work for deck levels. Plus they cut the square holes in the top of the saucer (for replacing burned out bulbs in the model)... those worked as windows if they are used for skylights.
So the corridors opening up to a commons area seemed like a good use of space that didn't work for other stuff. You have a row of tables along the top balcony and a series of tables below all with a nice view out the windows. The skylight is above a stairwell that connects the two commons areas.
If this seems odd to you, I suggest that you might need to get out more... this is not an odd design. I've been in quite a few buildings and ships that have similar arrangements. I guess if you've never been to a city you might never have seen this before, but it is really quite common (even one of my homes as a child had a similar indoor balcony setup).