Fwiw, another thing that would speak strongly in favour of direct 1:1 communication between hardware and plugin: Recording any parameter movements.
Even if you own both the hardware and the plugin, it's quite a PITA to do something such as simple as to record, say, a wah (obviously without recording it as audio data) that would then be played back by the plugin. Requires Command Center and DAW actions.
And now, let's take that a step further. Let's assume the hardware would be, say, Mackie HUI (or whatever is the latest most common DAW controller standard) compatibel. You could then as well just control pretty much anything with it if you wished.
And with HXN, there'd be complete bidirectional communication.
I really can't see any downsides to this approach (others than the developers having to spend quite some labour to do the initial work), unless someone wanted the plugin to be something entirely different from the hardware - which IMO would be quite a step back.
In fact, the not-100%-compatibility right now is what's forcing you to always re-load your patches in HX Edit, just to make sure they're still properly working in the hardware - and vice versa. Because in case you have lots of stomp switching happening on the hardware, that isn't represented in the plugin. The other way around, if you started in HXN, you'd still have to set up all the switches and what not in HXE or on the unit.
All that would be stuff from the past.
Add to this: With the Stadium, Line 6 seemed to have upped their interface game quite a bit (which is at least great on paper, only time will tell about the actual udio interface performance). Then there's the option to already send out keyboard commands, so you could possibly control most of what you'd otherwise do manually during DAW recording. The hardware controlling HXN directly IMO would be the next level of that.
Very obviously, I have no idea whether any of that would even be possible, but I'd defenitely dig it a lot.