Bachus,
ABSOLUTELY! Something you can add to a MIDI keyboard (including 88 Hammer action)

And there is plenty of options for MIDI controllers to use with a module...getting better all the time. BUT....take a look at the T5 for example...how many MIDI (function) switched does it have...LOTS AND they are for the most part where they need to be. One thing I wish I had right now is a strip of many MIDI switches 36 or so. A narrow strip to stick on the very bottom (top of the keys) on my MIDI keyboard for control of most common items needed on a regular basis while using styles, AND the switches need to be quiet. I hate hearing switch noise as I run the machine! It does not exist today. I can get by with other options...but not as good.

As you know I am involved in the vA2.
I will be doing a lot of review,demo soon.
I am still learning it and it will take a little time to be sure I understand before saying how it is in each respect.
Dan is very helpful, and I hope he does not tire of my questions and requests for improvements (if any).

Imagine a T5 module on top of a MOXF or any other PRO keyboard...you would have the best of both words.
BUT Pro's in a band environment do not typically use a arranger.
One thing that really works well is to add a 88 key hammer action below the arranger keyboard....but that's mostly for home use, not gigging for obvious reasons.

I think Ketron caters to accordion, guitar, etc players & that's where a module works well. The others really do not cater to that group as far as I know.

I think software arrangers is the answer, vs a module. Having a 22" touch screen above the keyboard is cool. Just need a MIDI keyboard that has essentially all the controls needed to have a optimized control of the arranger.