One reason for passing MIDI through the DAW rather than just tracking the audio is that MIDI is much easier to edit than audio. Tracking e.g. a mod wheel movement and not quite getting it right can be corrected easily in a DAW MIDI track, with audio only recording you have to keep trying takes until happy.

Another is that despite the apparently more complex setup it simplifies connections and allows the use of the DAW's MIDI facilities which can be considerable.

Another is that if a synth's controls send as well as react to MIDI it becomes possible to overdub a succession of control changes that could not be done any other way. Unless you have more than the conventional number of hands, that is.

There are quite a few MIDI merge/expansion hubs on the market, but as soon as you have two pieces of kit that both use the same channel and can't be changed the DAW route that can distinguish MIDI ports as well as channels is the one that will work while a stand-alone MIDI hub that works by channel only won't.

Thank you.  I clearly have some learning to do about this.
 
I don't really think that I need midi data out on the modules I am looking at (like the Integra 7, Nord A1R) as well as my Moog.  I only need audio out of them.  I understand how midi data is useful for VSTis, but what I really need to do is just "control" the modules with my FA-08.
 
Am I missing something (or alot of things :) )?

One thing midi out would do for a module would be to allow the PC to take in and save your custom program settings on the module. OTOH if you stick to the module's factory programs or if you can store your custom settings overwriting a factory program, you might not need to use midi out. But if you need custom settings saved along with the songs that use the module, you would need to grab them by sysex from the module into the DAW.
 
The MOTU MIDI Express XT and Micro Express USB seemingly allow offline ("standalone") patchbay, merging, and "processing", which would mean you don't have to turn on your PC to control various modules from one keyboard. The less expensive MIDI Express 128, or much less expensive "Fastlane USB" needs a PC to route or merge MIDI data.

I was looking at both of those.  I was researching the Micro Express USB earlier today, but I don't know how it can be truly standalone if it is USB powered...
 
Thank you for your help - I'm still learning.

Well, USB doesn't have to be from a computer. If it's plugged into a powered hub or iphone wall charger, then it's standalone.

Good point....

husker
I don't really think that I need midi data out on the modules I am looking at (like the Integra 7, Nord A1R) as well as my Moog.  I only need audio out of them.  I understand how midi data is useful for VSTis, but what I really need to do is just "control" the modules with my FA-08.
 
Am I missing something (or alot of things :) )?

I'll try and explain a bit better...
 
As an example, I'll use my DSI Mopho desktop module. It doesn't have many controls, and some are pre-configured to e.g. the filter resonance and cutoff while others are assignable in the patch. All however send MIDI as well as control whatever synth function they're programmed to do.
 
So I might have, say, note, velocity, aftertouch, modulation wheel, pitch bend and an expression pedal on a controller connected to it via the DAW, but I might want to add in more modulations/control changes than that allows me to do in one go (and I'll probably want to adjust things post recording). So if I record a pass through as MIDI I can then replay the recorded MIDI through the synth again while adding more control commands from the Mopho's knobs.
 
With my Waldorf modules that becomes even more important as there are combinations of controls Waldorf's matrix controller layout doesn't allow you to select at the same time. So if I want to e.g. make changes to the filter and ADSR at the same point in the music I can't by manipulating the synth controls. But I can record the MIDI sent by the filter controls then overdub the MIDI sent by the envelope controls. While if I recorded purely as audio I would only be able to control whatever parameters a combination of my abilities, the controller, the synth and the number of hands and feet I have make available at the same time.
 
Put another way, recording as MIDI then overdubbing MIDI CCs removes the limitation of only being able to do so many things at the same time.