For someone who understands bike wiring and components, this thing just adds cost, complexity, and more wiring. Ex: Simply run a wire from the horn button to the horn, that's all it needs.
For someone who has difficulty with the perceived complexity of traditional wiring, I can see where the m-unit creates a level of organization. Button/switch inputs simply wire to one labeled side, the other labeled side simply wires out to each individual component. The 'rats nest' stays inside the box.
Myself, I've been watching to see if someone will come out with a next generation control system. Similar to model train digital control, and the X-10 network. Those are mature and established technologies, yet offer an even simpler solution to wiring complexity.
Power and ground goes to all components. A decoder at each gadget 'listens' to signals on the power wire, and will turn the device on or off. No more rats nest.
Imagine the thick multiwire harness that currently goes into the headlight bucket being replaced with just power and ground. Opens up doors to simpler/cleaner 'in frame' wiring. With a good frame ground, you'd just need the one power wire going to various devices. The 'command' signals travel in that power wire. How simple is that?
For more excruciating pain, google "model train DCC" and "X10 network"...
That's exactly what the M-unit is about, simplifying, and eliminating the rat's nest, and there is an element to it that is similar to the "decoder" thing you are talking about, the M-button which hooks up to the M-unit:
Funny you should talk about model railroading, as that is my other hobby. I have been using DCC for a long time now and it actually is much simpler than the old block control system- now that was a rat's nest of wiring! See an example of the old type block control (note, not mine!):
DCC is much simpler in that it is combining power and data and sending both out to the rails at the same time, and in each model locomotive, there is a decoder that will only filter the data at the frequency it is tuned into, so you can have several locomotives on the same length of track that can move at different speeds or directions. With this version, you literally have just two wires to the track, positive and negative. The only other wires you have are to light the buildings and operate switches.
With the old block system, you had to isolate sections of a length of tracks into "blocks", in order to run more than one locomotive on that same length (because all locomotives received an equal amount of electricity), each block had its own throttle control, and when one locomotive passed from one block into another block, you had to toggle your throttle to that new block to continue operating the locomotive, hence the king of all rat's nest you see above.
Believe it or not, now DCC is now on its way out, and the new technology is bluetooth. You are now operating your trains from your smartphone, and the rails are not even powered (which is a huge gamechanger because you now no longer have to keep the rails clean, free of interference, or otherwise shorting out). Each locomotive has a small battery and a radio receiver.
Below is a picture of part of my small layout in the basement: